It was created during subglacial eruptions during the ice age. Its shape makes it distinctive; according to geologists, it is probably a crater plug. In spite of its steep slopes, it is not too difficult to climb, and the view from its top on a fine day is to be remembered. Keilir is the most distinctive landmark of Reykjanes and a symbol of the Reykjanes peninsula. On top of the mountain is a concrete table with a view direction map on a metal plate.

Location: 4x4 cars can drive on Höskuldarvegi and there is parking at Oddafell and a trail to Keilir.

From Höskuldarvellir there is only a 3 km walk to Keilir.