Enough to make your head swim isn't it? The world's largest pool holds 66 million gallons and is so big you can even sail boats use it.
The Crystal Lagoon at San Alfonso del Mar resort, Chile, is enormous and comes with its own fake beach. A quick dip in this mammoth structure 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 man-made lagoon is set halfway up the country's Pacific coast, in the city of Algarrobo, and is filled with crystal clear seawater.
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