Where is the largest pool in the world ?

A lagoon with salty waters located in Chile, in a Resort called San Alfonso Del Mar in Algarobo, is acknowledge by the Guinness World Records as the largest swimming pool in the world. 

This pool is 1013 m long and and covers 8 hectares in size. It holds holds 66 million gallons of water which took from the Pacific Ocean and then filtered and treated before it is supplied to the pool. It took five years to be build for the total cost nearly £1billion and the annual maintenance bill will be £2million.

 Its turquoise waters are so crystal clear that you can see the bottom even in the deep end.
It dwarfs the world's second biggest pool, the Orthlieb ? nicknamed the Big Splash ? in Morocco, which is a mere 150 yards long and 100 yards wide. An Olympicsize pool measures some 50 yards by 25 yards.

The saltwater pool contains 250,000 cubic metres of water and is navigable in small boats Chile's monster pool uses a computer- controlled suction and filtration system to keep fresh seawater in permanent circulation, drawing it in from the ocean at one end and pumping it out at the other.

The sun warms the water to 26c, nine degrees warmer than the adjoining sea.
Chilean biochemist Fernando Fischmann, whose Crystal Lagoons Corporation designed the pool, said advanced engineering meant his company could build "an impressive artificial paradise" even in inhospitable areas.
"As long as we have access to unlimited seawater, we can make it work, and it causes no damage to the ocean."