Kleifarvatn is the largest lake on the Reykjanes peninsula, and it's located along the tectonic fissure zone of the Mid Atlantic. It’s a highly volcanic place both above and below the water, and inside are a series of dramatic explosion craters up to 97m deep. There are no visible surface drainage as no rivers run to or from it, the water levels are actually regulated below the earth with ground water. The lake has diminished since earhtquakes in 2000 but it remains the third largest in Iceland. Soar over Lake Kleifarvatn on our Countless Craters tour, but be careful though: it is said to be the home of a whale sized worm monster!