The rescue divers were indispensable in the rescue and subsequent salvage operation, making a total of 648 deep-water tethered dives. They dived first to the wreck, where they anchored guide wires for the rescue bell to the escape hatch on the submarine. When the rescue bell became fouled on the 4th rescue trip, they attempted to unfoul the lines and get it to the surface. Each dive entailed considerable risk for the divers due to risk from the bends and "narcosis of the deep," a hallucinatory condition.