The largest swimming pool in the world is the San Alfonso del Mar seawater pool in Algarrobo, Chile. It is 1,013 m long and has an area of 8 ha , it was completed in December 2006.  It was listed officially as the largest swimming pool by area in the Guinness Book of World Records.

The pool holds a staggering 250 million liters (66 million gallons)  of water and is the equivalent to about 6,000 8-meter long pools. Located about 90 kilometers (56 miles) from Santiago, San Alfonso del Mar is a major tourist attraction and popular destination for both Chileans and tourists from around the world.

photos source: TwistedSifter