Archive for July 28th, 2010

The Pools and Reefs of Niue

Wednesday, July 28th, 2010

Niue’s limestone heart is also credited with the excellent quality of its drinking water and the clarity of the surrounding nearshore waters, since rainwater – instead of running off the island directly to the ocean and carrying soil and detritus with it  – tends to filter into and through the porous bedrock until it emerges in clear springs. 

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Take an oceanfront spring, add a fringing reef or two to close it in, and you have yet another one of Niue’s fun features: natural freshwater swimming pools.

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Actually, the pools are mostly sea water, but have a thin layer (about a foot or two thick) of fresh water thanks to the springs discharging from fissures in the cliff.  The fresh water, being less dense, sits atop the denser salt water, and the fun thing is, you can see (and feel) the difference between the two types of water as you’re swimming. 

Here, the camera’s sitting in the fresh water layer, so you can see the surface of the water in the top half of the photo, and the top of the salt water layer in the lower half of the photo.

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Ripples in the halocline between the fresh and salt water sometimes made for a blurry view of things in the lower layer (that’s S as she dove down into the brine), and the chilly temperature of the spring water encouraged swimmers to stay down in the warmer salt water layer as much as possible.

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The pools were like a snorkler’s playground, with the usual beautiful tropical fish (in the salt water layer), caves and arches to swim through, and best of all – no sharks!

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The sharks are on the other side of a vigorous surf break…

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But even with a good surf running across the reef the visibility was quite good.

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K was sad to miss the rare calm day that would have allowed a full day in the water without dodging these breakers.

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18°58.52’S 169°54.28’W   26-Jul-10 03:45 UTC