The Sulphur Mountains are to the south of the Langahlid ridge on the Reykjanes Peninsula.  They have been very volcanically active before and after the settlement of the country, and lava flows from them are conspicuous on the surface all the way down to the Herdisarvik cove in the south.

The Scot, W.C. Spence Paterson, encouraged English merchants to start mining the almost pure sulphur supplies in the mountains around 1880.  The mining activities did not last long, because they had to break through a 3-4 m thick lava sheets to get to the sulphur and the transport via the Grindaskord Route to the trading post in Hafnarfiord was difficult.