Oceanography: Death in the Depths

While Apollo 9 astronauts were preparing for outer space, two crews of U.S. aquanauts began new missions to determine how well man can exist in inner space—the underwater depths.

Near San Clemente Island off the California coast, the Navy's trouble-plagued "yellow submarine," Sealab 3, was lowered 610 ft. to the floor of the continental shelf. Then instruments indicated a helium leak in the still-unoccupied deep-sea habitat, and Aquanaut Berry L. Cannon, 33, and two companions were sent below to make repairs. They descended to the 610-ft. level in a pressurized personnel transfer capsule (PTC) and were opening a hatch to...

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