This pictorial article appeared in The Guardian in the UK- it is a simple little article but what a great wee story!!New Zealand is made up of many islands but two comprise the majority of the country and they are prosaically named North Island and South Island– I’ll let you work out the geography inherent in these names. (We also have a West Island but the people who live there call it Australia!!)
At the ‘top’ of the South Island is the Nelson Lakes National Park. It is among the western ranges of the Southern Alps and apart from the main two lakes, Rotoiti and Rotoroa contains many more smaller and much smaller lakes, one of which can claim to be The Clearest Lake In The World. Some claim!!Distilled water has a visibility range of between 70 and 80 metres! The visibility in Blue Lake in the Nelson Lakes National Park has been scientifically verified as having in-water visibility of 76 metres!!This extraordinary clarity is due to the very simple process of filtration. Practically all of the water that arrives in Blue Lake originates in Lake Clarence just a kilometre or so away to the south and water leeches out of Clarence and seeps through the glacial moraine material before seeping into Blue Lake- excruciatingly sediment free.Of course when it rains water flows into the Blue Lake from the surrounding mountains and as a consequence the water becomes less clear but remarkably all of the water in the lake drains out and is replaced over a period of about 24 hours!
The Department of Conservation has strict guidelines in place to preserve the pristine nature of this body of water even to the extent that visitors are prohibited from diving in it, and of course obvious restrictions as regards tramping, camping and associated water activities.
A wonderful place.