Brennisteinsfjöll ("Brimstone mountain") is a minor ridge with crater rows and small shield volcanoes in the Reykjanes peninsula in Iceland, about 20 km or 10 miles south of the capital Reykjavík. There was a lava flow south from Brennisteinsfjöll to the coast at Herdísarvík bay. Previously it was thought that this lava flow ceased before the settlement of Iceland, but this is now not thought to be the case as the coast road (now Route 42) was covered in lava at one stage. As the name suggests, sulphur is found here. Brennisteinsfjöll is geothermal.