One of the most important swimming coaches in U.S. Olympic history never really learned how to swim.

Soichi Sakamoto, who died in 1997 at the age of 91, was a sixth-grade science teacher in Hawaii when he formed the Three-Year Swim Club in 1937 for approximately 100 children of impoverished local sugar plantation workers.

"They had no bathing suits, very little food," Julie Checkoway, author of “The Three-Year Swim Club: The Untold Story of Maui’s Sugar Ditch Kids and Their Quest for Olympic Glory,” told NBC News.

Inspired by the great Hawaiian swimmers of the past like Duke Kahanamoku and previous, smaller-scale success, Sakamoto promised the children that with three years of his rigorous, never-before-seen training, the best of them would represent the United States in the 1940 Olympics.

"He knew nothing about mainstream swimming techniques," Checkoway said. "He used intuition and the scientific method."

For example, Sakamoto invented interval training in swimming. Inspired by Nordic track-and-field trainers, Sakamoto deduced that cardiovascular performance improved when swimmers alternated between going hard and fast, then slow and deliberately.

Without a pool, Sakamoto's charges swam upstream in irrigation ditches, which built up their resistance training.

"That was an intuitive thing," Checkoway noted. "But it ended up being one of the most scientifically important training methods.”

Sakamoto also emphasized land training more than other swimming coaches. "Their land training included running alongside his car up a hill," Checkoway said laughing.