The event at the Culver City Aquatics Center aimed to raise money for underserved children who cannot afford to get swimming lessons.
Pledging participants hoped to swim 2,462 miles collectively by midnight, amounting to the distance between Los Angeles and New York.
Drowning is the leading cause of death for children under 14 years old in the state of California.
"According to statistics, 10 kids die every day in the United States from drowning," said Larry Turkheimer, co-founder of the Los Angeles Tri Club. The club organized the event.