Mýrdalsjökull The South

This gorgeous glacier is Iceland’s fourth-largest ice cap, covering 700 sq km and reaching a thickness of almost 750m in places. The volcano Katla snoozes beneath, periodically blasting up through the ice to drown the coastal plain in a deluge of melt water, sand and tephra. Local operators run tours along the glacial crown as part of longer trips. Don't explore the area on your own; the ice is unstable and the track to the caldera can be impossible to navigate.