While Alvin is 23 feet long and 12 feet high, the pressure hull that houses the pilot and scientists is only a small portion of the sub. This titanium ball has an outside diameter of 82 inches and an inside diameter of 78 inches. Here, pilot Steve Faluotico navigates Alvin along the seafloor. It's very cramped inside the sub, which typically caries two scientific observers in addition to the pilot. The scientists sit with their legs alongside each other while the pilot crouches on a tiny padded bench. Dives may range from six to ten hours. A typical dive lasts eight hours.

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