Apr 10, 2026
The Hengill Volcanic System
Meet the volcano in our backyard!
Iceland is well-known for being a very volcanically active island. Roughly one-fourth of the island is an active volcanic zone. On average, an eruption occurs every four years, with the most recent eruption occurring in 2025 on the Reykjanes peninsula. This abundance of volcanic activity is also the reason that Iceland can harness geothermal energy.
The Hengill system is an active volcanic system 20 km from Reykjavík. It is roughly 60km long, consists of a fissure swarm and a central volcano, and contains a high temperature field. The magma from the volcanic system heats the bedrock up, which in turn heats the groundwater, resulting in the necessary resources to create geothermal energy.
ON Power’s Hellisheiði and Nesjavellir Geothermal Power Plants are both operating within the Hengill volcanic system. This is one of the largest geothermal systems in Iceland. It supplies both power plants with the heat needed to produce hot water and electricity due to the magma chambers and intrusions below the earth’s surface.
This volcanic system is roughly 200,000 years old. Historically, the system erupts once every 2,000 years. It last erupted roughly 2,000 years ago, but there are no indications that an eruption will occur soon. On a geological scale, a few hundred years is a very short amount of time.
The Hengill area is popular with locals and tourists alike. There are mountains, hot springs, furamoles, streams, valleys, and many areas noted for their colorful geothermal landscapes.
Hiking, mountain biking, ATV and buggy tours, horseback riding, and relaxing in hot springs are all popular activities. ON Power maintains 120km of hiking trails in the area, and provides information on the different trails, including a hiking map.
Hengill is on the route for the Golden Circle, South Coast, and Volcanic Way. It includes Hveragerði, a town famous for its geothermal activity, and Reykjadalur, one of Iceland’s most popular hot springs and hiking trails. You can also visit a smaller geothermal area called Hveradalir just down the road from the Hellisheiði plant before or after your visit to the Geothermal Exhibition.
The mountains you can see behind the Hellisheiði plant are part of this volcanic system – we call them the volcano in our backyard. You can learn more about this volcanic system and Iceland’s geothermal energy sector by booking your visit to the Geothermal Exhibition.
