Viti Crater Lake

Víti sits inside the Askja caldera, in Iceland's remote central highlands — not the Víti at Krafla of the same name. It is a roughly 150-metre explosion crater from the 1875 eruption, filled with an opaque, milky-blue lake at about 22°C. Visitors climb down the crater wall to swim in it. Öskjuvatn, the deepest lake in Iceland, lies right beside it. Reaching the crater is a summer-only trip over rough F-roads.