Vatnajökull National Park, Iceland
Lava field at Eldhraun, Vatnajökull National Park, Southern Region, Iceland
CREDIT: FEIFEI CUI-PAOLUZZO/GETTY IMAGES
Dominated by a 3,000-square-mile ice cap of the same name, Vatnajökull is a chilly wonderland of caves, craters, glacier-capped volcanoes, and waterfalls. Perhaps the most famous falls is Svartifoss, surging over hexagonal lava-rock columns.