Deep-Sea Submersibles

Diving to the depths of the ocean took thousands of years to accomplish. The first deep-sea divers used nothing but weights to make their way to the seafloor. But increased pressure and lack of oxygen proved to limit the ability to stay underwater for very long. The first advancements in deep-sea exploration had to first sustain and protect humans from the perils of the deep.

The first written account of diving is in the Epic of Gilgamesh. Gilgamesh, a Sumerian king of Uruk, pursues immortality and dives after a special plant in the primordial abyss.

“Gilgamesh opened a conduit to the Apsu and attached heavy stones to his feet. They dragged him down, to the Apsu they pulled him. He took the plant, though it pricked his hand, and cut the heavy stones from his feet, letting the waves throw him onto its shores.”

Aristotle writes in his Historia animalium of sponge divers using some sort of breathing apparatus to travel deep underwater. Many interpret this as the first mention of diving bells, while others believe he is referring to a snorkel.

“Some divers, when they go down into the sea, provide themselves with a breathing-machine, by means of which they can inhale the air from above the surface while they remain for a long time in the water. Nature has provided the elephant with something of this sort by giving him a long nose.” -Historia animalium

In the text Problemata, often attributed to Aristotle, the author(s) writes of sponge divers who fill their ears and mouth with oil shortly before diving and then spit it out at the seafloor in an effort to protect their ears from the pressure. This text also includes the first description of a diving bell:

"...they enable the divers to respire equally well by letting down a cauldron, for this does not fill with water, but retains the air, for it is forced straight down into the water."

Known as skandelopetra, the Greek diving technique requires a tether and weight. Divers fasten themselves with rope to a surface boat and use the heavy weight to plunge down to the seafloor. After gathering as many sponges as possible with held breath, a topside person pulls them up.

Guglielmo de Lorena invents the first diving bell, an upside down bowl that allows divers to breathe for extended periods of time. Accounts of the feat claim Lorena’s bell allows divers to stay underwater for one to two hours. He uses the bell to explore the wreckage of a sunken ship in a lake by Rome.

Cornelius van Drebel of the Netherlands constructs a wooden submarine for King James I of England. The submarine is propelled by 12 oarsmen who use waterproofed leather sleeves to row through ports. Cans containing an air-purifying agent are opened periodically to replenish the air supply.  It is noted that the submarine is able to travel along the Thames River at depths of 15 feet (4.6 m) for several hours.

Dr. Edmund Halley devises a lockout dive bell, which allows the divers to come in and out of the lowered bell. To extend the time divers can stay underwater, his system replenishes the air in the bell by lowering a barrel filled with fresh air. When the diver leaves the bell a smaller metal bell sits atop their head with a tube running back into the main bell.

Robert Fulton builds the Nautilus, the first metal submarine, for the French government. Tear-drop shaped and 21 feet (6.4 m) long, the iron frame was wrapped in copper plates. A pilot used a hand crank to power the propeller and take on ballast water to make it sink. After a successful demonstration, Fulton became impatient when Napoleon Bonaparte was slow to respond and disassembled the submarine. It proved difficult to convince governments of the submarine’s potential considering it was such a new technology.

The HMS Challenger expedition conducts the first comprehensive study of the deep sea. Scientists use dredges and trawls to collect specimens from the bottom of the seafloor and the open ocean. The expedition lays the groundwork for the field of oceanography and future study of the deep sea.
 

Simon Lake builds the first “modern” submarine, the Argonaut I. The 30-horsepower gasoline engine drew air from the surface through a pair of tubes and enabled the Argonaut I to sail more than 2,000 miles (3,200 km). During one perilous expedition the Argonaut I traveled from Cape May to Sandy Hook, New Jersey during a storm that sank 100 other ships. Famous author Jules Verne  (20,000 Leagues Under the Sea) was so inspired by the successful mission he wrote Lake a congratulatory letter.

Barton and Beebe set a record dive of 3,028 feet (923 m) below the surface using the Bathysphere.

“When once it (the deep ocean) has been seen, it will remain forever the most vivid memory in life, solely because of its cosmic chill and isolation, the external and absolute darkness and the indescribable beauty of its inhabitants.”-Beebe

Barton Otis designs his Benthoscope, an improved, steel version of the tethered Bathyscaphe that could protect one observer down to a depth of 6,500 feet (1981 m).  The Benthoscope conducts several dives off the coast of Santa Barbara, California. The deepest, a dive to 4,500 feet (1,372 m) deep, breaks the previous record set by Beebe and Otis in the Bathyscaphe. Otis was attempting to breach 6,000 feet (1,829 m) but needed to abort at 4,500 feet (1,372 m) when the lights malfunctioned.

The University of Washington develops the Special Purpose Underwater Research Vehicle (SPURV), an autonomous underwater vehicle (AUV) which is funded by the Office of Naval Research (ONR). The SPURV is capable of diving up to 10,000 feet (3,048 m) for up to four hours. The SPURV is used to study the ocean in supporting capacity through temperature and conductivity measurements.

As recreational diving becomes mainstream, both the general public and industry become enchanted by the deep sea. An explosion of new submersibles are built.

“As surface craft progressed century-by century from muscle, through sail, steam, diesel-electric and nuclear power, peaceful undersea explorers merely dabbled beneath the surface from cable-suspended spheres and open-bottomed diving bells. Then, in less than a score of years, mankind virtually leap-frogged to the greatest known ocean depths and produced an astounding array of undersea vehicles for science, industry and recreation.”-Manned Submersibles

Jacques Cousteau designs the Denise SP-350 submersible, also known as the Diving Saucer or La Soucoupe Plongeante. The life support system and controls are contained within the hull with the two occupants, while the batteries, buoyancy system, propulsion, and lights remain on the exterior. It is designed with a steel hull and can dive to depths of 1,150 feet (350 m) for up to five or six hours. The Diving Saucer sets the standard for submersible design due to its unprecedented maneuverability, interior comfort, transportability, and superior ports for viewing the ocean world.

" . . a scrutinizer, a loiterer, a deliberator, a taster of little scenes as well as big. She gave us six-hour periods in which to study accurately the things below” -Jacques Cousteau
 

Trieste dives to the bottom of Challenger Deep in the Mariana Trench, the deepest point of the Earth’s seafloor, as part of the United States Navy’s Project Nekton near Guam. Ultimately, the size of the submarine is deemed too cumbersome for routine exploration of the deep sea. A bathyscaphe, the Trieste can move up and down, but its maneuverability is limited.

Edwin Link conducts the first saturation dive as part of his Man-in-Sea project. Robert Stenuit is the first aquanaut, and spends 24 hours and 15 minutes underwater in Link’s submersible decompression chamber (S.D.C.) at a depth of 200 feet (61 m). This initial saturation dive proves humans can breathe and survive under pressure for extended periods of time.

John H. Perry, Jr., a Florida newspaper publisher, becomes enchanted by recreational diving and builds the Perry Cubmarine, a submersible meant for the everyday explorer. Ultimately, recreational diving by submersible does not pan out, and the Cubmarine finds its way to the Woods Hole Oceanographic Institution (WHOI) to study the Cape Cod Bay and nearby Georges Bank. The institution first leases the submarine in 1962 to study whale acoustics, and the Cubmarine is then later donated to WHOI in 1966. It carries two people up to 165 feet (50 m) underwater for up to five hours. WHOI uses the submarine to explore the Woods Hole Passage.

Perry and his newly formed Perry Submarine Builders becomes the largest producer of manned submersibles in the world.

The US Navy nuclear attack submarine Thresher sinks to 8,400 feet (2,560 m) of water off the coast of New England. The inability to rescue the 129 men trapped in the submarine causes the Navy to convene the Deep Submergence Systems Review Group in Washington, D.C. to assess the current field of deep-sea exploration. The meeting prompts all experts in the field to renew their efforts in submersible innovation. 

CURV (Cable-controlled Undersea Recovery Vehicle), the first operational remotely operated vehicle, is built by the US Navy. It is built for the purpose of retrieving torpedoes used in Navy training operations. Unlike submersibles, CURV is unmanned, tethered to a ship above, and operated from aboard the ship. CURV is most notable for its recovery of a lost nuclear hydrogen bomb off the coast of Spain. The success of CURV prompts the creation of several more CURV robots and sparks a whole new means to explore the deep sea without endangering human lives.

Allyn Vine is an oceanographer with Woods Hole Oceanographic Institution and proposes a deep-sea submersible for ocean exploration. WHOI and the US Navy partner to build the submersible, DSV-2, which is based on Harold “Bud” Froelhlich’s Seapup concept design. Named Alvin, in honor of Allyn Vine, the submersible is commissioned and undergoes its first test dive in 1964. When initially built, Alvin is 22 feet (7 m) long and 16.5 tons (15 tonnes). Bill Rannie joins Froehlich and Vine on its first dive to 35 feet (11 m).

Alvin is to become the most famous submersible, and the only submersible to become commonly known by the general public. As of 2025, it is still operational (though with many significant upgrades).

The Reynold’s Metal Company (known for their aluminum Reynold’s Wrap) begin a a massive campaign to promote the use of aluminum. The Aluminaut, a deep-sea submersible, is the most interesting element of that campaign. It is capable of diving 15,000 feet (4,572 m) with up to 4 passengers. During its 6 year life, the submarine explores all over the world.

“The Aluminaut is the first major response to the challenge of full scale deep-ocean research and exploration. With its 15,000-foot depth capability, self-propulsion, 80-mile range and 32-hour routine submergence time, the Aluminaut can explore the very bottom of 60 percent of the ocean areas of the world. Beyond question, it is the forerunner of tomorrow’s deep-diving undersea fleet to probe the mysteries of the oceans.”- Undersea Technology, 1964

General Dynamics, the nation’s largest military submarine producer, launches its Star line of submersibles, which eventually consists of three submersibles.

The Star II was later acquired by Hawaii Underwater Research Laboratory (HURL) and renamed Makali’i. Between 1981 and 1987 HURL operated the Makali’i, providing scientists access to depths of 400 m (1200 ft.) for 4 to 6 hours at a time. Through six 5- inch viewports a pilot and an observer could view the ocean world around them.

Launched in 1966, Star III was capable of carrying a two-person crew and as much as 1,000 pounds of scientific equipment to a depth of 2,000 feet (610 m). The sub and its occupants could remain underwater for up to 120 hours. The submersible was gifted to Scripps in 1970 and was used for underwater mapping. A press release by UC San Diego writes that the Star III “can accommodate the latest tools of underwater technology, including manipulators, lights, and photographic and electronic equipment.”

The first Pisces submersible is built by International Hydrodynamics Ltd. in Canada. The series of submersibles are initially designed to support both the booming fossil fuel industry as it expands into the deep ocean and the laying of telecommunication cables on the seafloor. Several of the submersibles become essential to early exploration of the deep sea. Pisces 4 and 5 eventually support the National Oceanic and Atmospheric Administration's (NOAA's) Hawaii Undersea Research Laboratory (HURL) in Hawaii.

Ed Link and John Perry team up to build the P-LC-4 or Perry-Link Deep Diver. The submersible is the first lockout submersible, which allows divers to exit and enter the submersible while at depth. Link partners with the Smithsonian Institution to allow scientists use of the submersible for marine science and exploration. One of the expeditions explores the Tongue of the Ocean in the Bahamas as part of Link’s “Man-in-Sea” project.

Notable scientists, including Sylvia Earle and Clyde Roper, are some of the first people to ever observe the deep sea near the Bahamas.

Cousteau builds two daughter subs to the diving saucer, the SP-500 Sea Fleas. These small submersibles allow one explorer to dive to a depth of 1,640 feet (500 m). Each is maneuvered by a joystick and has a robotic arm used for sampling. The Sea Fleas are used primarily for underwater filming, and Cousteau’s films bring the awe and wonder of the ocean to everyday people.

“Two funny little devices that look like turtles with their feet, head and tail pulled in, float on the ocean before diving into the depths: these are the Sea Fleas.”- The Cousteau Society
 

The US Navy builds and tests the Hikino, the first submersible with a fully acrylic pressure sphere. Hikino is purely a test vehicle, however, it is critical to the development of submersibles in the 1970s, an era that embraces the acrylic sphere. One complaint about submersibles in the 1960s is the lack of view ports for observation of the surrounding sea. The development of the acrylic sphere allows for an unobstructed panoramic view. 

A cable holding Alvin snaps and the submersible sinks to the seafloor. Though no people are aboard, the scientists’ lunch (a bologna sandwich, soup, and apple slices) remains aboard. Surprisingly, upon collection a year later there is no evidence of decay. This becomes known as the the Alvin Lunchbox Experiment and sparks interest in microbes, pressure, and their role in decay.

Reynold’s Aluminaut conducts two 14 hour dives to rescue and return Alvin.

A crew of six, led by Jacques Piccard, drifts from Florida to Maine for 30 days along the Gulf Stream in the Ben Franklin submersible. The ground-breaking expedition jointly run by the US Navy and NASA maps the continental shelf, monitors light levels, observes sea life, records sound from the surrounding ocean, and measures the Gulf Stream’s current speed. In addition to understanding the Gulf Stream, the mission also studies the habits of the crew to understand how isolation from society affected human behavior and psychology. Observations from the study influence future Apollo and other space flight missions and guide NASA experts on how to address the isolation involved with travel in space. 
 
During the expedition, NASA’s Apollo 11 lands on the moon, an event that completely buries the Ben Franklin’s mission from public awareness. However, the Gulf Stream Drift Mission is considered one of the most important oceanographic missions of its time.

"This voyage will loom almost as large in the history of oceanography as the lunar landing caused it to do in the annals of astronautics." -Jacques Piccard

It becomes apparent that submersible operations are costly, and leasing them is not profitable. The steep price to lease a submersible is unattainable for scientists with small budgets.  The booming industry suddenly sees several submersibles idle. With prospective buyer numbers diminishing, builders cease projects already underway and eat the cost rather than complete the submersibles, which can be worth up to $10 million upon completion. The Navy stops leasing private submersibles and halts production of a submersible under construction.

“I will be honest with you. This Administration cannot rush full speed ahead into marine development programs. The realities of national priorities and continuing inflation demand Executive discipline. All Federal expenditures have undergone sharp review. In many cases, we were forced to make painful reductions.” —Address by Vice President Spiro Agnew Fifth Annual Conference of the Marine Technology Society 16 June 1969, Miami Beach, Fla.

The boom of the 1960s is followed by a more constrained decade. This next generation of submersibles relies upon the advancements of the 1960s. However, cost considerations now influence new designs to have depth limits of less than 2,000 feet (610 m). Production of a submersible is geared toward commercial needs, such as those of the oil and gas industry, rather than the pursuit of exploration, which has very little financial resources or backing. A typical submersible now has panoramic viewing via an acrylic bubble, a simple design, and shallow depth limits. 

Submersible Nekton Beta suffers a major accident, taking the life of Larry A. Headlea. It is the first deadly accident to befall the submersible industry.

Edwin Link designs the Johnson Sea Link for the Smithsonian Institution to use for scientific research. The submersible is Link’s second generation of lockout subs, following the Deep Diver, which was decommissioned due to faulty metal that compromised the integrity of the submersible. 

The National Oceanic and Atmospheric Administration’s Manned Undersea Science and Technology Program begins. It aims "to develop, promote, and support a national, civilian, operational capability for man to work under the sea to achieve a better understanding, assessment, and use of the marine environment and its resources." During the first year the program uses eight different submersibles, including WHOI’s Alvin and the Smithsonian’s Johnson Sea Link, to conduct various research projects. Some of the projects include an assessment of the lobster stocks in the Gulf of Maine, a study of the Hudson Canyon near New York, and observations of the walrus population structure, social behavior, and reproductive biology in the Bering Sea. The program continues through 1980 when it is reorganized as the Office of Undersea Research.

Alvin’s personal sphere is replaced by a titanium sphere which allows it to dive to 12,000 feet (366 m). Over its lifetime, Alvin will undergo several upgrades to remain one of the most cutting edge scientific submersibles.
 

The Johnson Sea Link is stuck on the ship wreck it is investigating and remains underwater for 24 hours, which causes the death of two Smithsonian employees including Ed Link’s son, Edwin Clayton Link, and Albert Dennison Stover. The cold water is not considered when calculating air supply, causing the rescuers to believe they had more time to save the two divers.

Pilots of the Pisces III become trapped 1,575 feet (480 m) deep while working on a transatlantic telephone cable off of the South West of Ireland. US Navy ROV CURV III successfully rescues the two pilots. The successful rescue by an ROV gets the attention of the deep-sea industry and by the mid-1980s ROVs handle much of the work once done by manned submersibles in the telecommunications and oil industries.

The FAMOUS expedition (French-American Mid-Ocean Undersea Study) was a large-scale, international endeavor to survey the ocean floor. Through a joint partnership, the American and French governments funded deep-sea submersibles to photograph and map the Mid-Atlantic Ridge, a mountain range at the bottom of the ocean where the North American tectonic plate meets the Eurasian and the African plate. American submersible Alvin and French submersibles Cyana and Archimede were used during this historic project.

Alvin discovers hydrothermal vents along the Red Sea Rift near the Galapagos. The discovery prompts a monumental shift in our understanding of life on Earth. The sun is not the only source of energy for life—chemicals spewed from the Earth can also sustain ecosystems. New species of Riftia tube worms and clams thrive in the hot waters spewing from the seafloor.

NOAA establishes the National Undersea Research Program (NURP), which provides funding and access to underwater technologies like submersibles and habitats. It is the United States’ only federal program that supports scientific exploration and study of the deep sea. The support of NURP allows for groundbreaking discoveries in deep-sea science.

The scientific community begins using the newly invented remotely operated vehicles (ROV). Canada’s Department of Fisheries and Oceans purchases one of the first ROVs used for scientific studies, the Remotely Operated Vehicle for Ocean Sciences, aka the ROPOS.

The invention of ROVs causes many of the big submersible producers to either go out of business or shift to other industries. Many submersibles are either put out of commission or up for sale. 

Robert Ballard uses Alvin to discover the Titanic shipwreck. The monumental discovery is covered by major news outlets across the globe and Alvin becomes a household name.

The first remotely operated vehicle (ROV) to be developed and built at an academic institution, the JASON, is launched at Woods Hole. ROVs continue to become an integral part of deep-sea exploration, and they soon become standard equipment in ocean science. ROVs do not require a human passenger and they soon replace some of the human-operated submersibles. 

The Japan Agency for Marine-Earth Science and Technology builds the Shinkai 6500, a manned submersible that allows three people to dive down to 21,000 feet (6500 m). It becomes the deepest diving submersible in active use. 

WHOI launches ABE, one of the first autonomously operated vehicles (AUV) used for scientific research. ABE is designed to survey the shape of the seafloor, monitor hydrothermal vent emissions, and measure magnetic properties of the seafloor. It is particularly good at locating and mapping hydrothermal vents and underwater volcanoes.  The benefits of using an AUV include its ability to work and maneuver without a human controller since the AUV’s route is preprogrammed. 

NOAA’s Sustainable Seas project launches. Run by Sylvia Earle and funded by the National Geographic Society, the project explores the deep-sea habitats of the 12 U.S. marine sanctuaries over five years. Submersible work is done using twins Deep Worker and Deep Rover. 

The Smithsonian Institution and IMAX Limited partner to film "Galapagos", a 3-D IMAX film that follows Smithsonian researcher Carole Baldwin as she studies the islands from the Johnson Sea Link II. The film debuts at the National Museum of Natural History's Johnson IMAX Theater.

During the decade of the Census of Marine Life, more than 6,000 potential new ocean species are discovered by the roughly 2,700 participating scientists from more than 80 countries. Census scientists search the global ocean to learn more about species as large as the blue whale and as small as a zooplankton or microbe. They sample from the world's coldest regions to the warm tropics, from deep-sea hydrothermal vents to coastal ecosystems. They track the movements of fish and dig up studies from long ago to learn what the ocean used to be like before the influence of humans. Many of the projects rely upon submersibles.

Sir David Attenborough narrates the BBC’s Blue Planet nature documentary. The Johnson Sea Links and Alvin are used to film footage for the episode “The Deep,” which captures footage of a diving sperm whale, bioluminescent jellyfish, and a whale fall. The documentary films sea creatures and behaviors never before filmed.

WHOI tests the AUV SENTRY, a fully autonomous vehicle that is the successor to ABE. SENTRY is specifically designed to navigate and map extreme terrain, and, in particular, locate and navigate around hydrothermal vents. 
 

The first of Triton’s submersibles, the Nemo, launches. This class of submersible uses an acrylic bubble, much like the Johnson Sea Link submersibles. The first couple of Triton submersibles are a great success and soon the company develops an upgraded model that can dive to 3,280 feet (1,000 m). The production of the massive acrylic bubble requires extensive ingenuity engineering. They are highly sought after by marine scientists due to their panoramic view, light weight, and maneuverability.  

Despite autonomous vehicles becoming better equipped to monitor and explore the deep sea, human occupied vehicles continue to be essential for understanding the deep sea. A renewed interest in reaching the deepest depths of the ocean and advances in technology support new and updated submersibles funded by private citizens and governments.  
 

Smithsonian scientist Carole Baldwin partners with Adriaan “Dutch” Schrier to use his 5-person “Curasub” in Curacao in the Deep Reef Observation Project (DROP). An avid diver, businessman Schrier builds his submersible so he can continue to explore the deep sea even after his body can no longer handle scuba diving. Inspired by the new fish he could now witness with the sub, Schrier invites Baldwin and the Smithsonian to join him on his dives.

Access to the Curasub submersible provides Smithsonian scientists with 
the extraordinary opportunity to study tropical-reef ecosystems from zero to 1,000 feet (305 m).

DROP uses long-term monitoring of temperature, pH, diversity, and abundance of deep-reef marine life, including the invasive Pacific lionfish to study deep-sea reefs. Smithsonian scientists begin to investigate how deep-reef communities are partitioned by depth, how environmental conditions change over depth and time, and what role deep reefs may play in the survival of shallow reefs above. Scientists will discover over 45 new species of deep-reef fishes and invertebrates over the course of the project and will discover a new tropical reef zone called the rariphotic zone. As of 2025, the collaboration between the Smithsonian and the Curasub continues.

Edith Widder films a live giant squid from a Triton submersible. For decades, the scientific community sought to capture a live squid in its natural habitat. In particular, the Smithsonian Institution, under the guidance of squid expert Clyde Roper, led the charge for the search. But despite several expeditions, it remained elusive. Widder modified her Eye-in-the-Sea camera that uses red light as the camera’s light source and doesn’t spook deep-sea creatures. Using a blue pulsing light that mimicked a jellyfish in distress, she lured the giant squid to her camera.

Blue Planet II releases and captivates viewers across the globe. The use of high definition cameras reveals an utterly stunning ocean. Filming of footage for the documentary is carried out on the privately funded research vessel Alucia and a Triton submersible carries the cameramen into the depths of the ocean. 

The Limiting Factor travels to the deepest point in each of the five oceans as part of The Five Deeps Expedition and studies the deep-sea environment. Commissioned by Victor Vescovo, the submersible is another example of private investors funding deep-sea exploration and research. 

Alvin undergoes a massive overhaul to update its sensors and interior. With an updated titanium hull and better seals it can now travel to a depth of 21,000 feet (6,500 m) and is now comparable to the capabilities of Japan’s Shinkai submersible. The update allows for the exploration of roughly 99 percent of the seafloor.