Pisces III's Oxygen Nearly Ran Out

On August 29, 1973, the two-man submersible Pisces III was laying transatlantic telephone cable 150 miles southwest of Ireland when a fouled towline opened its rear machinery hatch, flooding the compartment and sending the craft 1,575 feet to the seabed. Inside, a 35-year-old engineer named Roger Mallinson and a 28-year-old pilot named Roger Chapman remained cold and wet in darkness, speaking and moving as little as possible to conserve oxygen. A 76-hour international rescue effort overcame broken ropes, leaks, and electrical faults before lifting Pisces III to the surface on September 1. When rescuers finally opened the hatch after 84 hours and 30 minutes, only 12 minutes of oxygen remained. It remains the deepest successful submarine rescue in history.

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