There is something about Blue Lake in New Zealand’s Nelson Lakes National Park that sets it apart from every other lake in the world — something so special about Blue Lake that human beings are not allowed to swim in it, and the local Maori tribes have traditionally considered its waters sacred.
The reason was always very plain to the Maori, and anyone who set eyes upon the waters of Blue Lake, or Rotomairewhenua, in the native language. But recently, a scientific study by New Zealand’s National Institute of Water and Atmospheric Research demonstrated this unique fact with hard data.
The study proved that Blue Lake has the clearest water of any lake in the world.
Visibility under the waters of Blue Lake can range up to 80 meters or more than 260 feet. Just for comparison, scuba divers will rate a body of water as having “outstanding” visibility if waters are clear for 40 meters.
If no one is allowed in the sacred waters of Blue Lake, where did these stunning photographs come from?
In 2013, Klaus Thymann, a Danish environmentalist and photojournalist, received special, one-time only permission to document the extraordinary beauty, and, of course, clarity of Blue Lake. The permission had to come not only from the New Zealand government and NIWA, but from the Maori, as well.
Back in 2011, NIWA ran its study on Blue Lake, and found through extensive testing, that the waters of the lake are as clear as distilled water.
“The theoretical visibility in distilled water is about 80 metres, as estimated from the best available instrumental measurements in the laboratory,” says Dr Rob Davies-Colley, an NIWA specialist in aquatic visibility. “So Blue Lake is a close approach to optically pure water.”
Of course, Blue Lake is not always as clear as you see in these photos. Rain can temporarily cause the pristine waters to become murky, but after a few days, the lake will clear up and return to its “optically pure” state.
“It’s also ‘refreshing’ to see that, while water quality has generally declined over recent years in most developed parts of New Zealand, in conservation land we have a freshwater that is truly outstanding in terms of optical purity,” said Davies-Colley.
For those of us who do not have access to sophisticated scientific instruments, Thymann ran a simple test. This final photo demonstrates the amazing clarity of the waters in Blue Lake.