Öræfajökull is a stratovolcano in Southeast Iceland (in Austur-Skaftafellssýsla county). The mountain is covered by a glacier cap which is also the southernmost part of Vatnajökull. It fills a large caldera at the summit of the mountain. Several outlet glaciers extend from the ice cap down the mountainsides and through valleys at the foot of the mountain. Among them are Svínafellsjökull, Virkisjökull, Kotárjökull, Kvíárjökull, and Hrútárjökull. On the northern side of the mountain is Hvannadalshnúkur, the highest peak in Iceland, standing at 2,110 meters. The entire Öræfajökull glacier is within Vatnajökull National Park, and much of the mountain as well.
Öræfajökull is a central volcano and has erupted twice in historical times: first in 1362, when Litlahérad was destroyed, and then during a smaller eruption in 1727. Significant damage occurred in both eruptions, accompanied by ashfall and glacial floods.
In November 2017, earthquakes occurred beneath the glacier, and dissolved chemicals were measured in Kvíá, a river flowing from the glacier, suggesting the presence of a new geothermal area underneath.