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).

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.

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).

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).

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).

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).