However, Blue Lake, as it’s known to visitors who hike within the mountains of Nelson Lakes National Park in New Zealand’s Southern Alps, is under severe threat of losing its purity.

Tourists visiting New Zealand’s Nelson Lakes National Park have been asked to wipe their shoes before entering Lake Rotomairewhenua. The waterbody, also known as Blue Lake due to its pristine ...

Editor’s Note: Call to Earth is a CNN editorial series committed to reporting on the environmental challenges facing our planet, together with the solutions. Rolex’s Perpetual Planet ...