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10:43 GMT, 21 May 2012 The Mail

At the San Alfonso del Mar resort in Chile, a quick dip could well turn into a marathon.

Swimming a length in this, the world's largest outdoor pool, would mean stroke after stroke for more than three fifths of a mile - that's
20 Olympic-size swimming pools.

The enormous man-made lagoon is set halfway up the country's Pacific coast, in the city of Algarrobo, and is filled with 66 million gallons
of crystal clear seawater.



It also hold the Guinness record for the world's deepest - so if you don't feel like diving 115ft to the bottom, it might be best to bring
some spare goggles.

The pool opened in December 2006 after nearly five years of construction work and is said to have set developers back as much as £1billion.

And on top of that eye-watering initial cost, it takes a further £2million a year to keep it in working order.