Skjuvatn

Öskjuvatn (Askja Lake) is a large glacial lake in Iceland, situated in the caldera of the Askja volcano under Vatnajökull glacier. With a surface area of approximately 11 km² and a depth of 217 meters, it ranks as the second-deepest lake in Iceland. The lake was formed following a major volcanic eruption in 1875.

Initial surveys in 1876 revealed a roughly circular lake with a diameter of about 4000 feet (1220 m), a depth of 232 meters, and water temperatures around 22°C. Over the years, its temperature fluctuated significantly; by 1907, it had cooled to 6.5°C. Notably, in 1907, two German scientists exploring the lake disappeared without a trace, and despite extensive searches led by vulcanologist Hans Reck, no evidence of their fate was found.

The lake's shape and depth have changed due to volcanic activity and eruptions. A bathymetric survey in 1963 provided key data, while a more recent assessment suggested the maximum depth might be greater than previously recorded. The lake’s floor has subsided since its formation, reflecting ongoing geological activity. Öskjuvatn remains a unique and dynamic feature of Iceland's volcanic landscape.