Askja Caldera

Askja is a massive active caldera located in the Icelandic Highlands. Inside the caldera lie two contrasting lakes, the deep dark-blue Oskjuvatn and the small crater lake Viti. Oskjuvatn is the deepest lake in Iceland and fills much of the caldera floor. The milky-blue water of Viti is warm and rich in minerals, and bathing is possible with caution. The surrounding black sand and lava fields resemble a lunar landscape once used by NASA for astronaut training.