Earth's Largest Underground Thermal Lake Found in Albania

Lake Neuron in southern Albania is the largest known underground thermal lake on Earth.

It is 138m long, 42m wide and holds roughly 8,335 cubic metres — over three Olympic pools of warm water.

The lake sits 127m below ground at the foot of a 100m vertical abyss called Atmos.

Czech speleologists led by Marek Audy found it in 2021 and mapped it with a 3D laser scanner.

Hydrogen sulfide in the water slowly turns the cave's limestone into soft gypsum.