The Sealab project, launched in 1969 off the shore of northern California, was the brainchild of a country doctor turned naval pioneer who dreamed of pushing the limits of ocean exploration like NASA did space exploration. The massive, 300-ton tubular structure was a pressurized underwater habitat, complete with science labs and living quarters for divers who would live and work there on the ocean floor for days or even months at a time. During the height of the Space Race, this daring program also tested the limits of human endurance and revolutionized the way humans explore the ocean.