Eldborg Crater

Eldborg is a crater so cleanly shaped that early Icelanders called it the fortress of fire — a steep-walled oval rising from the lava at the foot of Snæfellsnes, in West Iceland. You reach it on foot from the Snorrastaðir farm, about 2.5 km each way across a moss-and-birch lava field. From the rim you circle the whole cone and look down inside — there is no way in — with the flat lava plain and distant fells all around.