The Hengill area is a mountainous region between Suðurlandsvegur and Lake Thingvallavatn, reaching from the eastern heath of Mosfellsheiði to Grafningsfjöll. The area contains most of the elements that make Icelandic nature so unique: interesting landscapes, hot springs and craters, varied vegetation, rivers and lakes.
The area is ideal for outdoor activities all year round. Reykjavik Energy has been working systematically for the benefit of people engaged in outdoor activities by developing a network of marked routes, information boards, hiker shelters and the publication of a hiking map since 1990. Reykjavik Energy currently manages a total of 130 km of marked routes in the natural paradise of Hengill. ON Power, a subsidiary of Reykjavik Energy, operates two geothermal plants on the periphery of Hengill: the Hellisheidi Geothermal Power Plant to the south and the Nesjavellir Geothermal Power Plant to the north, where the geothermal energy under Hengill is harnessed for the production of hot water and electrical power.