Skutustadagigar

On the southern shore of Lake Mývatn, a cluster of green, symmetrical craters rises from the grass — the largest pseudocrater field in Iceland. They look volcanic but never erupted. About 2,300 years ago lava flowed over wet marsh and trapped steam that blasted the crater shapes from below. Footpaths loop among and over the cones for wide views over the shallow lake, its islands and waterbirds. It is a protected natural monument, and its rootless cones are studied as a model for similar shapes on Mars.