Tindfjallajökull is a stratovolcano in the south of Iceland. It has erupted rocks of basaltic to rhyolitic composition, and a 5-km-wide caldera was formed during the eruption of the 54,000 year old Thórsmörk Ignimbrite. It is capped by a glacier of 19 km². Its highest peak is Ýmir (1462m), which takes its name from the giant Ýmir of Norse mythology.