Woods Hole Oceanographic Institution (WHOI) operates the US Navy-owned Deep Submergence Vehicle (DSV) Alvin as a national oceanographic facility. A typical eight-hour dive takes two scientists and a pilot as deep as 4,500 meters (14,764 feet), a depth capability that encompasses 86 percent of the seafloor. When working at maximum depth, it takes about two hours for the sub to reach the seafloor and another two to return to the surface. The four hours of working time on the bottom are crammed with carefully planned photography, sampling, and experiments conducted by the scientists using three 12-inch-diameter viewports. Alvin can hover, maneuver in rugged topography, or rest on the bottom.

Typically, three video and two 800-frame, 35-ram cameras are mounted on Alvin’s exterior for either automatic or selective operation. Because there is no light in the deep sea, the sub carries 12 lights to illuminate the bottom. Two hydraulic, robotic arms manipulate sampling and experimental gear specially designed to work with their “hands.”

A sample basket or sled mounted on the front of the sub carries a variety of instruments that includes sediment corers, temperature probes, water samplers, and a biological sample pump. Scientists using the sub can bring up to 1,000 pounds of their own gear.

Alvin is especially useful to such observational sciences as biology and geology, but marine chemists, physicists, and engineers are also among its users. The sub is probably most famous for locating a hydrogen bomb accidentally dropped into the Mediterranean Sea in 1966 (two years after the sub's delivery to Woods Hole), for its exploration of deep-sea hydrothermal vents discovered some two decades ago, and for its survey of the sunken ocean liner Titanic.

Alvin Dive Statistics, 1964-1999
Total Dives	3,515
Total Depth	7,224,392 meters
Average Depth per Dive	2,055 meters
Total Time Submerged	24,068 hours
Average Time Submerged per Dive	6.85 hours
Total Persons Carried	10,540
Dive Purpose Breakout
Geology/Geophysics	1,285
Biology	1,240
Chemistry/Geochemistry	389
Certification/INSURV	245
Inspection/Search/Recovery	171
Engineering/Equip Tests	84
Orientation	74
Navy Test/Survey	27

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