Among the scenic landmarks of Iceland's desert highlands, the vast stratovolcano Askja is the most visited -- and not just for its stark, elemental beauty and grandeur. If the weather cooperates, you can take a warm unforgettable swim in a crater lake with milky-blue, sulfurous water. Trips to Askja often extend to Kverkfjöll, a mountain spur protruding from the northern margin of Vatnajökull amid a bleak expanse of rugged hills and gritty lava. The Kverkfjöll region is suffused with geothermal activity, and hot springs sculpt elaborate ice caves as they emerge from the glacier's edge.

These areas can only be accessed in sturdy 4WD vehicles or on organized tours. All accommodations are in mountain huts, and all food must be brought in. Clear skies can switch suddenly to rain, and snowstorms can arise even in midsummer. Askja can be reached on day tours from the Mývatn, but seeing Kverkfjöll requires at least 1 night apart from civilization. Two nights at Kverkfjöll should be the minimum, since the best hikes take the better part of a day.