Submersibles Through Time

The world's first submersible (1620)
Records show that British carpenter and gunner William Bourne designed the world's first truly submersible boat as early as 1578, but it was not until Dutch physicist Cornelius Drebbel modified Bourne's plans 40 years later that the man-powered submarine finally came into existence. Shaped like an enclosed rowboat, the vessel included ballast tanks for stability and a system of screws for managing the amount of water in her tanks, enabling the submersible to sink or rise. Complete with six oars (and 12 oarsmen) for propulsion, a snorkel-like apparatus for air, and leather hides for waterproofing, Drebbel's third version of this contraption could descend to a depth of 15 feet, allowing it to travel down the Thames River.

The bathysphere (1930)
While many of the world's navies have long used highly developed submarines in military operations, scientists began their underwater exploration with more primitive vessels. These early manned submersibles were often heavy, cramped metal containers, dangled like anchors into the sea. In 1930, William Beebe (left) and Otis Barton (right) became the first humans to observe the deep ocean in their newly designed bathysphere, gazing through quartz-glass portholes three inches thick. By 1934, the team reached a world-record depth of 3,028 feet, more than twice as deep as their previous dives.

Trieste (1953)
An untethered, deep-diving bathyscaphe (literally "deep boat"), Trieste was the brainchild of Swiss inventor August Piccard, who in the 1930s reached unprecedented altitudes of almost 52,000 feet with his unique pressurized aluminum gondola. Piccard modified his atmospheric balloon concepts to design the Trieste, using gasoline, which is lighter than water, for buoyancy. In 1960, the submersible dove more than 35,000 feet to the deepest point on Earth, the Marianas Trench, withstanding a crushing pressure of eight tons per square inch.

Alvin (1964)
As the oldest manned research submersible still in operation, Alvin boasts an impressive résumé. Having logged over 4,000 dives so far, the titanium sphere was the first manned vessel to visit the wreckage of the RMS Titanic. Alvin has also helped researchers discover approximately 300 new animal species, including foot-long clams and giant red-tipped tubeworms. Thought lost in 1968 when her support cables failed and her crew abandoned ship, the craft spent 11 months on the seafloor, sustaining only minor damage. Near-freezing temperatures and a lack of oxygen kept even the lunches left onboard perfectly preserved—if a bit damp.

Johnson Sea-Link (1971)
The Johnson Sea-Link class of highly maneuverable vessels can accommodate up to four people each in dives of as deep as 3,000 feet, but its chief claim to fame is its use of highly specialized equipment. Using manipulator arms, suction devices, and rotating sample-collection tools, the futuristic Sea-Link makes it possible for crew members to execute from within the submersible nearly every task once performed by divers. Equipped with sonar, laser-aimed cameras with arc lights, and a five-foot-wide acrylic viewing sphere, the Sea-Link is a proven research vessel.

Clelia (1976)
This "yellow submarine" has a lot of sensitive equipment on board, but she's more durable than she looks. Clelia is designed to withstand possible tumbling and turning in waves of up to six feet, even with a full crew onboard, yet can be balanced underwater to provide researchers with an exceptionally stable platform from which to observe. Equipped with sophisticated cameras and 500-watt metal halide lights, Clelia assisted scientists trying to determine why the 729-foot iron-ore carrier, the Edmund-Fitzgerald, sank to the bottom of Lake Superior in 1975.

Mir I and II (1987)
Slow-moving and battery-operated, the Mir I and II are nevertheless two of the deepest-diving vessels in the world. Able to descend nearly 20,000 feet, they can access up to 98 percent of the world's oceans, making them ideal for everything from research to underwater filmmaking. In fact, director James Cameron took advantage of the submersibles' 5,000-watt lights when filming his blockbuster movie Titanic. Despite stretching over 25 feet long, each Mir has a personal sphere just seven feet in diameter for her three-person crew.

Autonomous Benthic Explorer (ABE) (early 1990s)
The first underwater vehicle of her kind, the ABE is a true robot, operating autonomously with no onboard crew or tethers to guide her. While the small, seven-foot-long vessel moves at a maximum rate of just two knots, she can cover large areas of underwater terrain as deep as 16,500 feet for months at a time, a task that would prove prohibitively expensive if attempted with manned or tethered machines. The ABE is programmed to perform several tasks on her own, such as navigating, taking photographs, collecting data and samples, even powering down or "sleeping."

Deep Flight I (1996)
Don't let the name—or the look—fool you. Deep Flight I's aeronautical-like design is ideal for the water. Forgoing the more traditional ballast systems used to sink and raise most submersibles, this vessel has short, inverted wings providing the "negative lift" needed to pull her downward at a rate of up to 12 knots. Deep Flight I is equipped to carry high-definition and IMAX video cameras, and is designed for deep ocean access. To operate the craft, a single pilot lies on his or her stomach, controlling the submersible with joysticks.

DeepWorker 2000 (1997)
Affectionately dubbed an "underwater sports car," DeepWorker 2000 is compact and relatively lightweight at 1.3 tons. Diver Phil Nuytten (pictured here) designed the craft to give researchers the ability to move as freely as scuba divers yet to far greater depths (2,000 feet). DeepWorker 2000 is controlled by a single pilot who serves as data collector, navigator, and camera operator. Steering the vessel with foot pedals, the pilot performs other tasks—such as cutting cables, lifting objects, and operating scientific instruments—using manipulator arms, which are jointed like human arms to allow for freer motion.

ROV Hercules (2003)
Scientists designed this remotely operated craft chiefly to study and recover artifacts from ancient shipwrecks, but Hercules can be used for a wide array of scientific purposes. Armed with a flexible set of multipurpose tools, one of the craft's two manipulator arms offers "force feedback," allowing operators miles away to better control the pressure the device applies upon more delicate specimens, such as boxes found aboard the RMS Titanic (pictured here). Equipped with a flotation device composed of glass and epoxy resin, Hercules can "fly" in any direction like a helicopter and will float gently to the surface if her thrusters stop turning, an innovation that could prove useful for future submersibles.