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From the Bottom Up

During a typical eight-hour dive, the Alvin personnel sphere carries a pilot and two science observers to the sea floor. This image of the sphere was taken with a fisheye lens with the camera set on the floor looking up. The pilot‘s viewport can be seen at the bottom of the picture. The big hole in the middle is the hatch, used to enter and exit the sphere, and outside of that is the sail and the ceiling of the sub hanger. The titanium sphere is 79 inches in diameter inside and the thickness varies between 1.94 inches at the thinnest point to 4.5 inches around the viewports.(Photo by Mark Spear, Woods Hole Oceanographic Institution)