The famous Askja Caldera in the Dyngjufjoll Mountains – is located on the northern side of the Vatnajökull National Park. Askja is a 50 square kilometers subsidence cauldron formed when a lava chamber just under the surface of the earth emptied in a volcanic eruption and the roof above it collapsed. In fact, Askja consists of three interlinked cauldrons, which makes it the best subsidence cauldron example in Iceland.
There you'll find the Öskjuvatn Lake, which has an area of 11 square kilometers and is the deepest lake in the country with a depth of 217m. Additionally, you'll see the beautiful Víti volcano, which contains a 60m deep geothermal lake filled with bright blue water at 22 degrees Celsius. It's almost like a surreal, natural Blue Lagoon inside a volcano.