Brennisteinsfjöll
Brennisteinsfjöll, or Sulphur Mountains, are a ridge of late Ice Age hyaloclastite mountains. The highest point is the lava shield Kistufell. Brennisteinsfjöll are lined with volcanic fissures that are not much older than Iceland's settlement. A geothermal area is located in the northern part of the mountains, where sulphur was mined around 1880 with little success. The mines are still visible.