Watch Voyages of Discovery online: Episode 5 Hanging by a Thread

Explorer Paul Rose tells the story of the USS Squalus submarine which became stranded on the bottom of the Atlantic in 1937. No one had ever been saved from a stricken sub beneath the ocean before, but maverick designer Charles Momsen, who had been ignored by the navy top brass, was suddenly called into action to bring up the crew. Rose meets the last living survivor from the sub and one of the men, now 103, who helped save him. The rescue kick-started a whole new era of technology, laying the foundation for modern deep sea diving.

click here to see where to watch or .