We can never know for sure who was the first person to dive beneath the waves in search of food or artifacts, but we do know that ancient peoples—perhaps as far back as one hundred thousand years ago—collected shells, shellfish, and other valuable undersea resources along the coastline (e.g., Will et al. 2019). As human use of the ocean grew for military, economic, and industrial purposes, so too did the need to know more about the ocean. Studies of marine biology, oceanography, and fisheries emerged as scientific quests to acquire knowledge of the sea for human purposes (e.g., Mills 2012).

In the next three chapters, we explore the approaches and technologies used to carry out ocean science—the methods of an oceanographer. Admittedly, a tour of methods might seem a bit like wandering through a home improvement store. (Indeed, oceanographers often shop at these stores—you can never have enough duct tape on board a rolling ship.) But a brief survey of these technologies will help you appreciate the myriad ways in which oceanographers are probing the world ocean. This appreciation will help you better understand the team approach to ocean science and the interconnectedness of processes in the world ocean.

My friend and colleague University of California (UC) Santa Barbara physical oceanographer Tommy Dickey (b. 1945) spent his career pushing the boundaries of ocean science through application of new technology. In his 2020 paper “New Discoveries Enabled by the Emergence of High-Resolution, Long-Term Interdisciplinary Ocean Observations,” he wrote:

The vastness and inhospitable nature of our oceans has limited our ability to understand oceanic phenomena and to make ocean predictions. Great progress in sampling the vertical and temporal variability of the ocean was made with new sensors and moorings in the period of 1980–2000; however there remain major challenges to adequately sample the full three-dimensional and temporal variability of the interior ocean.

3.1 The Birth of Oceanography

While many important scientific expeditions took place in the 19th century, one above all, the Challenger expedition (1872–1876), brought together the interdisciplinary approaches that would characterize the field of oceanography in modern times. Oceanographer and marine biologist Henry Bigelow (1879–1967), who helped found the world-famous Woods Hole Oceanographic Institution (WHOI) in Massachusetts, wrote in his 1931 textbook, Oceanography, “Students of the history of science may well date the birth of modern oceanography from December 21, 1872, the date when put to sea from Plymouth, England.” Indeed, the Challenger expedition was the first devoted entirely to ocean science. A decade after their voyage, Scottish expedition leader Sir Charles Wyville Thomson (1830–1882) and Canadian oceanographer John Murray (1841–1914) wrote:

The vast ocean lay scientifically unexplored. All the efforts of the previous decade had been directed to the strips of water round the coast and to enclosed or partially enclosed seas. . . . This consideration led to the conception of the idea of a great exploring expedition which should circumnavigate the globe, find out the most profound abysses of the ocean, and extract from them some sign of what went on at the greatest depths. (Thomson and Murray 1885, p. l)

The Challenger expedition covered 79,277 miles (127,584 km) of ocean and gained fame for its ambitious plan and the magnitude of its accomplishments. Its results filled 50 printed volumes. But perhaps most lasting among its contributions was its influence on the way oceanographers sample the ocean, a sampling approach that remains an integral part of oceanographic research more than 150 years later.

3.2 Sampling over Space

Since the days of the Challenger expedition, shipboard oceanography has used a sampling approach based on grids of points stretched over a region of interest. As Thomson describes it, “At intervals as nearly uniform as possible, we established 362 observing stations” (Thomson 1878, p. xi). Thomson’s observing stations are now known as hydrographic stations, or simply stations. Each point on the grid represents a station. The line along which the ship moves from station to station is known as a transect. Hydrographic stations mark the spots where geological, chemical, physical, and biological measurements and samples may be taken. Of course, oceanographers may carry out measurements and take samples along the transect while underway, too. The number of stations and length of the transect depend on the number of days allotted to the expedition and the type and amount of work that the expedition team desires to carry out. 

The distance between samples of different regions of the ocean—horizontally or vertically—defines the spatial resolution of the measurements. As someone living in the 21st century, you have undoubtedly witnessed increases in the spatial resolution of televisions and smartphone cameras. Spatial resolution defines the smallest object or feature that may be resolved or distinguished by the display or sensor in your television or smartphone camera—such as 4K resolution (and soon 8K and 16K). Similarly, for oceanographers, spatial resolution refers to the smallest features that may be distinguished in a particular set of data. At higher spatial resolution, oceanographers can identify an individual underwater mountain versus a blob of mountains. They can discriminate the fine details of different water temperatures (depicted as colors) instead of one blotch of the same temperature. Low spatial resolution occurs when oceanographers have to take samples far apart in distance or when a sensor can only measure broad swaths of the ocean. To obtain higher spatial resolution, oceanographers must take more samples in a given area or build sensors that detect smaller features. But there are limits. 

Time, technology, and funding don’t always permit the highest spatial resolution. A compromise has to be made between where oceanographers sample and how much they sample: more locations with fewer samples at each location or fewer locations and more samples. Taking and processing more samples takes more time. Observing smaller details of the ocean demands better technology. But time and technology require money that is not always available. 

An excellent example of the application of grid sampling can be found in the California Cooperative Oceanic Fisheries Investigation (CalCOFI), which has been conducting oceanographic surveys off the coast of California since 1949. The original grid in 1950 included hundreds of stations along the California coastline and parts of Baja. But since 2004 the survey has been limited to between 75 and 109 stations over a smaller area. Today CalCOFI samples an area of 73,184 square miles (189,547 km²), a considerable expanse but still less than 0.05 percent of the world ocean. Nevertheless, CalCOFI ranks as “the longest-running oceanographic monitoring program on the planet” (e.g., Koch 2019).

Combinations of technology and ships now provide an ability to sample the ocean at spatial scales spanning twelve orders of magnitude—from kilometers down to nanometers (e.g., Dickey 1990; Branson et al. 2016). The challenge for 21st-century oceanographers will be to connect the dots—to find the connections—between processes at each of those scales (e.g., Dickey 1991).

3.3 Sampling over Time

Ocean properties also vary with time. Similar to spatial resolution, we refer to temporal resolution (i.e., time resolution) as the interval of time between samples. A once-a-month sampling program has a temporal resolution of one month. A daily sampling regime has a temporal resolution of a day, and so on. But why is this important?

Imagine that you were tasked with summarizing the details of every movie playing in a 21-screen multiplex, all with different start times. To complete the task, you would have to move from theater to theater and watch only a few minutes of one movie before moving on to the next. You would never be able to see one movie in its entirety. And if you spent more time on one movie, you would sacrifice your knowledge of other movies. 

The ocean is like a multiplex in which thousands—if not millions—of movies are playing simultaneously. What’s more, the plot of each movie keeps changing as different characters and events arise. When you return to the first theater, there’s no guarantee that the original film will still be playing. It’s maddening, but somehow, through persistence, repetition, well-honed methods, and careful sampling strategies, oceanographers have begun to make sense of it all. 

In the CalCOFI program, oceanographers obtain one set of samples per station approximately every three months. Such sampling permits oceanographers to track changes on seasonal scales, but what about day-to-day or week-to-week changes? Oceanographers simply don’t have the tools or manpower to sample the ocean over all relevant scales of space or time. But, as we shall see in the chapters ahead, new technologies are helping to improve ocean sampling at ever-finer spatial and temporal scales.

3.4 The Challenge of Pressure

Nearly every technology developed for ocean exploration beneath its surface confronts one inevitable question: How deep can it go without being crushed? Many a machine has been lost (some with lives aboard) because of the intense pressure exerted by the ocean. Pressure is the reason why it’s easier to explore outer space. A dozen humans went to the Moon half a century ago, traveling a distance of 238,855 miles (384,400 km), but until 2019, only three humans had been to the Challenger Deep, the deepest location in the world ocean, a mere 6.8 miles (10,925 m) deep. Though dozens of people have now descended to the Challenger Deep (see below), extreme water pressure remains a barrier to all but the most specialized technologies.

Physicists define pressure as the force exerted by a fluid (a gas or a liquid) on an object immersed within it. In the ocean, every 10 meters of water depth, about 33 feet, increases pressure by about 14.7 pounds per square inch, or 1 atmosphere (atm) at sea level. Earth’s atmosphere, on average, extends about 7.5 miles (9.17 km) above us. So the pressure exerted by about 33 feet of water equals the pressure exerted by about 7.5 miles of gases in our (one) atmosphere. For simplicity, oceanographers often express water pressure in units of atmospheres. The calculation is quite simple:

P (atm) = z (m) / 10 (m/atm) + 1 (atm)

(Eq. 3.1)

where P is water pressure, z is depth, and 1 atm represents the pressure at sea level (from the atmosphere pressing down on the ocean).

The simple math makes it apparent: you don’t have to go very deep to experience great pressure. At 800 times the density of air, water exerts a much greater pressure on objects immersed within it. At a depth of a hundred feet (roughly 30 m), a diver experiences three times the pressure they would experience at sea level. Free divers—persons who dive with no scuba gear and rely only on holding their breath—experience even greater pressure. The current no limits freediving record depth of 702 feet (214 m), held since 2007 by Austrian Herbert Nitsch (b. 1970), converts to a water pressure 22 times the pressure at sea level (e.g., The Salt Sirens 2021). Imagine a newborn baby elephant (about 300 lbs) balanced on a USB wall charger (about 1 square inch on each side). That’s what a free diver experiences at those depths. 

3.5 The Undersampling Problem

The challenges of sampling a difficult environment across multiple scales of space and time have led to what is known as the undersampling problem in oceanography. Oceanographers do not yet possess a sufficient number of measurements to develop a complete understanding of ocean processes. Advances in technology—especially satellites and robots—have improved the spatial and temporal resolution of observations. Though some oceanographers contend the physics of the ocean is adequately sampled (e.g., Munk 2000), many parts of the ocean, especially the deep ocean, and many biological processes remain undersampled (e.g., van Haren 2018; Claustre et al. 2020).  

3.6 Modern Oceanographic Vessels

Oceanographic research vessels form the backbone of ocean research in the 21st century. While their ability to provide much-desired spatial and temporal resolution remains limited, ships offer a platform for nearly every other type of technology used to study the ocean. Humans working aboard ships can perform feats no modern robots can come close to. Ships enable diverse teams of oceanographers from all over the world to carry out collaborative research.

Modern oceanographic research vessels—designated by R/V in front of the ship’s name—serve several functions. Under the supervision of a trained captain and crew, they provide a safe, comfortable, mobile habitat for dozens of scientists and technicians. Among their many attributes, 

• They provide a stable platform for launching and deploying a variety of oceanographic instruments above, below, and on the surface of the ocean.
• They permit scientists to access remote ocean locations, including the central gyres of the major oceans, ice-covered oceans, and remote islands.
• They offer state-of-the-art navigation capabilities, providing precise locations for sampling (underway or on station) and the ability to return to those exact locations in the future.
• They offer state-of-the-art communications and telepresence capabilities, allowing oceanographers and crew to download satellite imagery and stream images to shoreside personnel and the public.
• They provide specialized cranes and winches for deploying oceanographic instruments, such as submersibles and robotic craft.
• They offer ample deck space, such as a fantail, a broad platform on the rear of a vessel, where oceanographers can work outside close to the waterline, and where portable vans (or clean rooms) can be installed for carrying out specialized analyses and experiments.
• They provide laboratories with benchtop instruments for at-sea analyses of collected samples, where live organisms may be observed, and where samples may be prepared and stored for shoreside analyses.
• They offer computing capability for storing and analyzing electronic data in real time or on demand.
• They provide mess halls and places to sleep, bathe, and relax (e.g., a lounge with a big-screen TV, a library, a gym, and, on some vessels, a sauna). Some of these spaces can also be used for meetings and conversations with colleagues.

Most oceanographic research vessels operate under the supervision of the University–National Oceanographic Laboratory System, better known as UNOLS. The UNOLS fleet includes five global-class ships, six intermediate-range oceangoing vessels, and seven regional/coastal-class ships. UNOLS also coordinates the use of nearly one hundred small research vessels (35–100 feet in length). UNOLS-approved vessels meet strict standards, including rules aimed at individual conduct, prohibitions on drugs and alcohol, and guidelines on privacy, discrimination, and harassment while on board (UNOLS 2021). Researchers who request use of a UNOLS vessel must adhere to these standards.

Oceanographers also make use of ships of opportunity, commercial vessels that regularly cross the ocean, such as freighters, tankers, cruise ships, and ferries. The Ships of Opportunity Program (SOOP) provides reports on weather conditions and deploys expendable profilers that measure properties of the water column, an unspecified volume of water from the surface to a particular depth. SOOP, managed by the National Oceanic and Atmospheric Administration (NOAA), currently collects weather and ocean data from more than 1,200 vessels.

It goes without saying that life aboard an oceanographic research vessel brings adventure, excitement, and a sense of camaraderie with fellow scientists. Crew and scientists typically work around the clock in shifts of four hours on and eight hours off or some variation thereof. With multiple teams of scientists carrying out different kinds of investigations, a research cruise may seem a little like a three-ring circus. But in the end, weather and equipment permitting, everyone accomplishes as much as they possibly can in the time allotted. It’s a lot of work, and the work can be exhausting, but you won’t get any sympathy from the crew. When I once complained on the R/V Oceanus about being tired, the galley person responded, “You can sleep when you’re dead.” 

3.7 Beneath the Surface

Technology that permits humans to travel beneath the surface of the ocean dates back at least to the fourth century BCE. The Greeks apparently figured out they could hoist a large metal pot over their head, walk out into the water, and breathe the air trapped inside. Thus was born the diving bell, a dome-shaped, air-filled chamber that permits divers to work at depth, even in modern times. Aristotle (384–322 BCE) mentions diving bells used by sponge divers in the Aegean Sea (Forster 1927). His student, Alexander the Great (356–323 BCE), purportedly used a diving bell to observe a “gigantic creature that took three days to pass by” (Bevan 1999). Of course, had he stayed submerged for such a time, he would have been dead from lack of oxygen. Obviously, you can’t believe everything you read in books.

Human desire to reach the deepest depths of the ocean finds a place in the 20th century as well. In the 1930s, two Americans, naturalist William Beebe (1877–1962) and engineer Otis Barton (1899–1992), built the world’s first bathysphere, a hollow steel sphere with transparent baseball-sized portholes for making observations. Lowered on a cable from a ship, the bathysphere—with the men bolted inside—made a series of successful descents, including one to 3,028 feet (923 m) on August 11, 1934. Beebe’s sketches and account of his dives resulted in a best-selling book, Half Mile Down (1934), the first work to document the strange and wonderful animals that inhabit the dimly lit waters known as the mesopelagic zone.

A few decades later, a similar vehicle, the bathyscaphe Trieste, enabled two men to reach the Challenger Deep, the first humans ever to do so. A bathyscaphe consists of a hollow steel sphere attached to a giant gasoline-filled “bladder,” which provides the necessary buoyancy for returning divers to the surface without a cable. On January 23, 1960, Swiss oceanographer and engineer Jacques Picard (1922–2008) and US Navy lieutenant-oceanographer Don Walsh (b. 1931) descended to 35,814 feet (10,916 m), setting a world record for the deepest dive. Their record would stand for 52 years (Walsh 1962).

3.7.1 SCUBA

No summary of underwater technology would be complete without mention of the invention that permitted humans to see the undersea world firsthand: the self-contained underwater breathing apparatus, better known as scuba. Invented in 1943 by French engineer Émile Gagnan (1900–1979) and French ocean explorer Jacques Cousteau (1910–1997), scuba permits humans to inhabit shallow waters for limited periods of time. Cousteau’s television series, The Undersea World of Jacques Cousteau (1968–1975), instilled in the public a love for the ocean and inspired the careers of many a marine biologist and oceanographer, including mine (Cousteau and Schiefelbein 2007). 

While typically limited to shallow waters (less than 130 ft), scientific diving—underwater observations, measurements, and experiments using scuba—provides a means for scientists to carry out direct observations or experimental studies for extended periods of time. In recent years, marine scientists have begun to use advanced scuba tools (i.e., advanced technical diving) to explore mesophotic coral ecosystems, deep, light-dependent coral reefs found at depths between 100 and 500 feet (30–250 m; e.g., Loya et al. 2019; Bell et al. 2022).

Scientific divers may also employ a shark cage (also invented by Cousteau)—a metal cage that permits safe viewing of sharks and other pelagic ocean species. Divers enter and exit the cage at the surface through an opening in the top. Once divers are inside, the cage descends to an optimal depth for viewing the animals. Though shark-cage diving is popular as a tourist adventure, the cages prove useful for scientific studies where direct observation is required, including estimates of animal length (e.g., May et al. 2019) and studies of feeding behavior (e.g., Becerril-Garcia et al. 2019). I’m told there’s nothing like meeting a great white shark face-to-face. Maybe some day you’ll get the opportunity.

3.7.2 Atmospheric Diving Suits

The atmospheric diving suit, or ADS—also known as an armored diving suit or articulated diving suit—allows divers to explore deeper waters. The ADS resembles a space suit, but it operates more like a submersible (see below). In fact, some authors classify the ADS as a one-person submersible. The ADS maintains sea-level pressure inside the suit—hence its name. This eliminates the need for decompression when the diver comes to the surface.

An early type of ADS, the JIM suit, enabled American marine biologist Sylvia Earle (b. 1935) to reach 1,281 feet (381 m) off the coast of Oahu in 1979. The dive lasted two and a half hours and set a record for the deepest dive at the time. During her dive, Earle observed bioluminescence in bamboo corals, a phenomenon not filmed until 2016 (Helgason 2016). The JIM suit—named after a diver named Jim—was also featured in the James Bond film For Your Eyes Only (Glen 1981) and a lesser-known sci-fi film, DeepStar Six (Cunningham 1989).

New-generation ADSs can reach depths of 2,000 feet (610 m). They incorporate various types of propulsion units and include LED lights, sonar, HD cameras, real-time atmospheric monitoring, and two-way wired and acoustic communication systems. In 2019, the US Navy teamed up with the National Aeronautics and Space Administration (NASA) to develop a diver-augmented vision device, a heads-up display system for dive helmets. Using the display, the diver can monitor a host of data and receive text messages from topside (such as ROSL, roll on seafloor laughing). The system can even provide augmented-reality displays, useful where visibility is poor (Melnick 2019; Naval Technology 2021). 

3.7.3 Submarines

Though predominantly used for military purposes, submarines, defined as a vessel capable of propelling itself underwater, also play a role in modern oceanographic research. Since 1993 oceanographers and the US Navy have collaborated on the use of nuclear submarines for oceanographic research, especially in the Arctic. The first mission, named SCientific ICe EXercise 1993, or SCICEX-93, carried five scientists aboard the USS Pargo, a Sturgeon-class fast attack submarine named after a fish. The success of SCICEX-93 spurred five more missions from 1995 to 1999. For security reasons the navy instituted scientific accommodation missions, or SCICEX SAMs, in 2000, in which trained navy personnel carried out oceanographic measurements without scientists on board. Scientists may access the data—once it’s declassified—through the National Snow and Ice Data Center (SCICEX Science Advisory Committee 2010). As a joint civilian-military program, SCICEX SAMs enable collection of data that would not otherwise be possible to obtain. Observations beneath the ice help verify above-ice satellite observations and further scientific understanding of the role of the Arctic in climate change (Morelo 2010). 

3.7.4 Submersibles

Small submarines, better known as submersibles, deep submergence vehicles (DSVs), or human-occupied vehicles (HOVs), play a larger role in oceanographic research than submarines, sacrificing speed for depth capability. Unlike submarines, submersibles require a transport ship to carry them to their dive location. And while typical naval submarines carry more than a hundred personnel, most submersibles carry only two or three. Typical modern submarines operate at depths less than 1,500 feet (457 m), but many submersibles can attain depths of 14,763 feet (4,500 m) or more. New generations of submersibles can now reach the deepest locations in the world ocean.

No submersible in the world can match the record of WHOI’s HOV Alvin—in operation since 1964—the only American scientific research submersible. Alvin has enabled the discovery of hydrothermal vents, helped find the RMS Titanic, and served countless scientists in pursuit of knowledge about the ocean (e.g., Humphris et al. 2014). As of 2020, the near-60-year-old vessel had logged 5,065 dives, carried 15,186 people, and spent 35,474 hours submerged. But Alvin’s most exciting days may lie ahead. In 2022, upgrades to the submersible allowed it to reach a depth of 21,325 feet (6,453 m), the deepest ever for the sub. It may now access some 98 percent of the seafloor. Despite the opinion of some that robots could better serve science at these depths, there’s simply no substitute for being there. As one ocean engineer put it, underwater cameras are “still a long way short of what the human eye can do” (Oberhaus 2020).

Still, the very deepest spots remain mostly unreachable. Only two submersibles, the Chinese Fendouzhe and the US DSV Limiting Factor, can reach the Challenger Deep today. Descending in the Limiting Factor in April 2019, American undersea explorer Victor Vescovo became the fourth explorer to reach the Challenger Deep and set a new world record for the deepest dive ever, reaching 35,853 feet (10,928 m). On July 12, 2022, American marine geologist Dawn Wright became the first Black person (and fifth woman) to reach the deepest spot on Earth with a 35,823-foot dive (10,919 m) aboard the Limiting Factor (Weinman 2022). More than two dozen people have now reached these depths (Kreier 2022). 

3.7.5 Undersea Research Stations

Undersea research stations—semipermanent structures designed for human habitation and scientific research on the seafloor—entered the human imagination long before they became a reality. Historians credit “freethinking” English bishop John Wilkins (1614–1672) as the first person to imagine permanent undersea colonies (Wilkins 1708; Matsen 2009). French writer Jules Verne (1828–1905) imagined a mobile underwater habitat in his epic novel Twenty Thousand Leagues Under the Sea (Verne 1870; translated by Miller and Walter 1993). Captain Nemo’s exploits aboard Nautilus inspired many an ocean explorer, including Cousteau (Matsen 2009). 

In the 1960s Cousteau and his team of divers built three stationary underwater living spaces on the seafloor of the Mediterranean and the Red Sea. The first, the cylindrical Continental Shelf Station Number One, or simply Conshelf I, was established at a depth of 33 feet (10 m) near Marseille, France. At 17 feet long and 8 feet high (about 5.2 × 2.4 m), it served as a kind of underwater tiny house complete with television, radio, and a record player. From September 14 through 21, 1962, French aquanauts Albert Falco (1927–2012) and Claude Wesley (1930–2016) spent a week on Conshelf I, the first humans ever to live underwater for multiple days. According to protocol, the men were required to spend five hours a day outside of the station carrying out observations of marine life and tending an underwater farm. When asked what he would like to do upon his return to the surface a week later, Falco simply replied, “To walk” (Cousteau and Dugan 1963, p. 324). 

A year later, the Conshelf II “village” was established in the Red Sea. The starfish-shaped main station, at 33 feet long (10 m), accommodated five men and included a parrot to warn of pressure changes. The undersea village also had a garage for a submersible, an equipment hangar, and a second station 82 feet deeper (25 m). This time, the aquanauts stayed a month. During the last four days of their residency, they were joined by Cousteau’s research partner and wife, Simone Cousteau (1919–1990), who became the first woman to live underwater. 

The exploration and research in these underwater habitats were captured in the documentary World without Sun (Cousteau 1964), which won an Academy Award in 1965 (Cousteau’s second in the category). That year the Cousteau team also established a much deeper habitat near Nice, France. Conshelf III, at 336 feet (102 m), housed six aquanauts who remained underwater for three weeks. The idea of people living and working beneath the sea was no longer a fantasy. Cousteau had made it a reality.

Cousteau’s success led to construction of similar habitats around the world. Since 1962 at least 70 underwater habitats have been built (Chamberland 2007). But don’t let that number fool you—many never made it beyond their first mission. Most no longer exist or have become manmade reefs. And only three ever accommodated aquanauts for longer than 30 days.

The only remaining undersea habitat dedicated to scientific research is Florida International University’s Aquarius Reef Base (1986–present), a 400-square-foot, six-person habitat in the Florida Keys. One other operational undersea habitat, the Jules Undersea Lodge (formerly La Chalupa research laboratory), serves as an underwater hotel and occasional classroom in a lagoon in Key Largo Undersea Park in Florida. In 2023, University of South Florida professor Joseph Dituri (b. 1968) set a world record for living underwater in the Jules Undersea Lodge (Kim 2023).

In 2020, Cousteau’s grandson, French ocean explorer Fabien Cousteau (b. 1967), and Swiss designer Yves Béhar (b. 1967) announced plans to build an underwater manned research station in 60 feet of water (about 18 m) off the coast of Curaço in the Caribbean. Named PROTEUS™, the planned habitat will accommodate a dozen aquanauts and have a capability to live-stream video in 16K resolution. About the project Cousteau says, “I’m just a crazy person with a dream that sees this as being not only possible—but absolutely necessary—for our future well-being” (Knapp and Jennings 2020). A partnership announced with NOAA in May 2023 may just help that dream come true (NOAA 2023).

3.8 Chapter References

Becerril-Garciá, Edgar E., Daniela Bernot-Simon, Marcial Arellano-Martínez, Felipe Galván-Magaña, Omar Santana-Morales, and Edgar M. Hoyos-Padilla. 2020. “Evidence of Interactions between White Sharks and Large Squids in Guadalupe Island, Mexico.” Scientific Reports 10: 17158. https://doi.org/10.1038/s41598-020-74294-4

Beebe, William. 1934. Half Mile Down. New York: Harcourt, Brace, and Company. https://doi.org/10.5962/bhl.title.10166

Bell, James J., Valerio Micaroni, Benjamin Harris, Francesca Strano, Manon Broadribb, and Alice Rogers. 2022. “Global Status, Impacts, and Management of Rocky Temperate Mesophotic Ecosystems.” Conservation Biology, e195235. https://doi.org/10.1111/cobi.13945

Bevan, John. 1999. “Diving Bells Through the Centuries.” South Pacific Underwater Medicine Society Journal 29(1): 42–50. 

Bigelow, Henry B. 1931. Oceanography: Its Scope, Problems, and Economic Importance. Boston: Houghton Mifflin. https://hdl.handle.net/1912/219

Branson, Oscar, Elisa A. Bonnin, Daniel E. Perea, Howard J. Spero, Zihua Zhu, Maria Winters, Bärbel Hönisch, Ann D. Russell, Jennifer S. Fehrenbacher, and Alexander C. Gagnon. 2016. “Nanometer-Scale Chemistry of a Calcite Biomineralization Template: Implications for Skeletal Composition and Nucleation.” Proceedings of the National Academy of Sciences 113(46): 12934-12939. https://doi.org/10.1073/pnas.1522864113

Chamberland, Dennis. 2007. Undersea Colonies: The Future of Permanent Undersea Settlements. Orlando: Quantum Editions.

Claustre, Hervé, Kenneth S. Johnson, and Yuichiro Takeshita. 2020. “Observing the Global Ocean with Biogeochemical-Argo.” Annual Review of Marine Science 12: 23–48. https://doi.org/10.1146/annurev-marine-010419-010956

Cousteau, Jacques-Yves. 1964. World without Sun. Columbia Pictures. 93 minutes. https://www.imdb.com/title/tt0058364/

Cousteau, Jacques-Yves, and James Dugan. 1963. The Living Sea. New York: Harper & Row. https://www.google.com/books/edition/the_living_sea/RH62lplz-2AC

Cousteau, Jacques-Yves, and Susan Schiefelbein. 2007. The Human, the Orchid, and the Octopus: Exploring and Conserving Our Natural World. New York: Bloomsbury. https://www.bloomsbury.com/us/human-the-orchid-and-the-octopus-9781596914186/

Cunningham, Sean S., director. 1989. DeepStar Six. Carolco Pictures. 99 minutes. https://www.imdb.com/title/tt0097179/

Dickey, Tommy. 1990. “Physical-Optical-Biological Scales Relevant to Recruitment in Large Marine Ecosystems.” In Large Marine Ecosystems: Patterns, Processes, and Yields. Edited by Kenneth Sherman, Lewis Alexander, and Barry Gold, 82–98. Washington, DC: American Association for the Advancement of the Sciences. http://www.opl.ucsb.edu/tommy/pubs/Dickeyscales1990.pdf

———. 1991. “The Emergence of Concurrent High-Resolution Physical and Bio-Optical Measurements in the Upper Ocean and Their Applications.” Reviews of Geophysics 29(3): 383–413. https://doi.org/10.1029/91RG00578

———. 2020. “New Discoveries Enabled by the Emergence of High‐Resolution, Long-Term Interdisciplinary Ocean Observations.” Perspectives of Earth and Space Scientists 1(1): 1–10. https://doi.org/10.1029/2020CN000129

Forster, E. S. 1927. The Works of Aristotle. Volume VII: Problemata. Edited by W. D. Ross. Oxford: Clarendon Press.

Glen, John, director. 1981. For Your Eyes Only. United Artists. 127 minutes. https://www.imdb.com/title/tt0082398/

Hegalson, Nicole. 2016. “First Video of Coral Bioluminescence in the Deep Sea.” Reef Builders. August 10, 2016. https://reefbuilders.com/2016/08/10/first-documentation-of-bioluminescence-in-the-deep-sea/

Humphris, S. E., C. R. German, and J. P. Hickey. 2014. “Fifty Years of Deep Ocean Exploration with the DSV Alvin.” EOS. June 3, 2014. https://eos.org/features/in-june-2014-the-deep-submergence-vehicle-dsv-alvin-the-worlds-first-deep-diving-sub-marine-dedicated-to-scientific-research-in-the-united-states-celebrated-its-50th-anniversary

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