Fleishhacker Pool was a public saltwater swimming pool located in the southwest corner of San Francisco, California and named after philanthropist and civic leader Herbert Fleishhacker. Upon its completion on 22 April 1925, it was one of the largest heated outdoor swimming pools in the world and remained open for more than four decades until its closure in 1971. It was eventually demolished in 2000.
The pool water was pumped from the Pacific Ocean, filtered and heated. The pool's heater could warm 2,800 US gal of seawater from 60°F to 75°F each minute. This resulted in a constant pool water temperature of 72°F. The water provided by a series of pumps and piping at high tide, directly from the Pacific Ocean, 650 ft (200 m) away. There was also a diving pool measuring 50 ft (15 m) square and 14 ft (4.3 m) deep and a two tiered diving tower.
After years of underfunding and poor maintenance, the pool was showing some deterioration when a storm in January 1971 damaged its drainage pipe. Because the repair costs exceeded the City's budget, the pool was converted to a fresh water pool which resulted in poor water quality. As a result of the poor attempt at conversion and resulting water quality, the pool was closed by the end of 1971.
In 1999, the San Francisco Zoological Society was granted ownership of the pool house. The swimming pool itself was filled with rocks and gravel, with the space now serving as a parking lot for the zoo. The poolhouse was derelict, neglected, and occupied by the homeless for many years until it was destroyed by a fire on 1 December 2012.