Tucked away in the remote mountains of Nelson Lakes National Park on New Zealand’s South Island is a lake so clear it reflects itself.

With visibility up to 260 feet, Blue Lake – or Rotomairewhenua in native Maori – is literally about as clear as bottled water. As a spring feeds Lake Constance slightly uphill, water trickles through a natural dam formed by landslide debris down into Blue Lake. The rocks and rubble of the dam essentially strip all of the water’s impurities as it flows into the lake, where it sits only for roughly a day before draining into a river. And that, ladies and gentlemen, is the natural filtration process responsible for the world’s clearest lake.

Visitors and divers aren’t usually allowed in Blue Lake, but photographer Klaus Thymann got government and Maori permission to take a helicopter there and explore the mystic blue-violet water with his camera. The outcome? Some of the most enchanting images you’ll see.

Underwater, the lush algae bottom of the lake reflects off its surface, creating an illusion-like pattern of rich green and blue tones. Thymann also photographed a massive draining sinkhole, which he told LiveScience he didn’t want to get too close to for fear of being sucked in. He wasn’t allowed to touch the bottom because of sacred Maori customs. Pretty magical stuff, huh?

Thymann’s Blue Lake photos are part of his Project Pressure, a non-profit organization he created to document (in spectacular fashion) the world’s glaciers as climate change continues to threaten them.

“During the next decade many glaciers will retreat or disappear,” Thymann says on his site. “Documenting glacier history pre-melt will provide future generations with a visual archive of the way the world was, and underscore the importance of preserving the balance of the world’s ecosystem.”

Awe-inspiring photography with an eco purpose – We love it.

Check out a few of Thymann’s most captivating images of Blue Lake below, and head over to LiveScience for a full slideshow.

caption id="attachment_11459" align="aligncenter" width="300" caption="Photo by Klaus Thymann"/caption

caption id="attachment_11458" align="aligncenter" width="300" caption="Photo by Klaus Thymann"/caption

caption id="attachment_11457" align="aligncenter" width="300" caption="Photo by Klaus Thymann"/caption