Grjótagjá is a small lava cave located near lake Mývatn. It features a geothermal hot spring inside. Grjótagjá was popular for bathing until the 1970s but fell out of use during eruptions from 1975 to 1984. However, the temperature is slowly falling down. Outlaw Jon Markusson lived in this cave in the early 18th century. The fictional characters Jon Snow and the wildling Ygritte were also filmed inside this cave in the TV series Game of Thrones. Photo taken September 21st, 2017.