Hrafntinnusker is a large obsidian field located in the highlands of Iceland, just east of the infamous Mount Hekla. Hrafntinna is the Icelandic name for obsidian. Obsidian is black and glassy, and forms when rhyolite cools very quickly. The surroundings of this area are not only colourful, but also filled with many hot springs, steam vents, boiling mud pits and ice caves. Despite the hard ice, there is actually geothermal activity happening under the surface so it is not recommended to enter the caves.
This area is only accessible by 4x4 vehicle, or of course by helicopter! The hiking trail Laugavegur crosses this area, and sometimes hikers will choose to stay in a Tourists Association hut built in 1977, located here.