Nesjavellir Geothermal Area

Nesjavellir is a high-temperature geothermal area on the northern slopes of the Hengill volcano, just above the southern shore of Þingvallavatn, where Route 435 from Reykjavík meets Route 360 along the lake. It is home to the Nesjavellir Geothermal Power Station, the second-largest in Iceland, and its white steam plumes are visible from much of the Þingvellir area. For Golden Circle drivers it works as a scenic back road into or out of Þingvellir rather than a stop with a ticket desk.

Set expectations before you go. The power plant's operational area is closed to the public and there is no visitor centre, so what you come for is the drive, the views over the lake and the hiking trails that start nearby. Our coach tours use Route 36 and do not pass this way; without a car, a private guided Golden Circle is the closest option, but ask before booking whether the detour can be included.

What is Nesjavellir?

Nesjavellir sits in one of the largest high-temperature areas in Iceland, the Hengill area, which ON Power describes as connected to three volcanic systems. Water heated by hot rock deep under Hengill rises through faults and fissures, and the national park notes that part of the water travelling south from Langjökull resurfaces here as steaming hot water instead of as cold springs in the lake.

People have looked at harnessing that heat for a long time. Test boreholes were drilled from 1947, construction of the plant began in 1987 and the cornerstone was laid in May 1990.

Nesjavellir geothermal power station

The station produces both electricity and hot water. According to ON Power's figures for its plants, Nesjavellir can deliver up to 300 MW of geothermal energy and up to 120 MW of electricity. In hot water, that is about 1,640 litres per second. That hot water travels by pipeline to the capital, where it provides a large share of the heating and hot water for the Reykjavík area.

You can see the plant clearly from the road, with its silver pipes snaking across the moss and steam drifting from its chimneys. You cannot go inside. If you want to learn how geothermal power works, the place for that is the Hellisheiði power plant on the other side of Hengill, which has ON Power's geothermal exhibition.

Route 435: the Nesjavellir road

Route 435, Nesjavallaleið, exists because of the plant. Reykjavík's district heating utility built it to carry the hot-water pipeline from Nesjavellir to Grafarholt on the edge of the city, and finished the road in the summer of 1988. It runs east from the Hafravatn area over the Mosfellsheiði moors and drops down to Route 360 just north of the power station.

For a Golden Circle driver, the appeal is the descent. As the road comes off the ridge, Þingvallavatn opens up below you with the plant's steam in the foreground, one of the best views of the lake from any road. The pipeline runs alongside much of the way.

Combining Route 435 with Route 360

The best use of Nesjavellir is as part of a loop. Drive out on Route 36 to Þingvellir in the morning, then return by Route 360 along the western shore of Þingvallavatn and Route 435 back to Reykjavík. Alternatively, follow Route 360 south past Nesjavellir to Úlfljótsvatn and the Sog and carry on towards Kerið.

Both roads are paved, but they are minor roads with more bends than Route 36, and Route 435 crosses exposed high ground. In winter, check road conditions on umferdin.is before choosing them over the main road.

Hiking near Nesjavellir

The Hengill area is the main reason to stop and get out of the car. ON Power and Reykjavík Energy maintain around 130 km of marked trails across Hengill, with information signs, the Múlasel hiking hut and a downloadable trail map in English. The area is open to the public year-round, though most of the trails are best walked between June and September.

Take the warnings seriously. Hot springs, hot streams and boreholes can scald, and the steam and gas around them can be dangerous. Stay on the marked paths, which also protect the fragile moss and wetland. If you have hiked Reykjadalur near Hveragerði, you have already been on the southern side of the same volcanic area.

Is Nesjavellir worth visiting?

Nesjavellir is worth it if you are driving yourself and want a quieter, more scenic route between Reykjavík and Þingvellir, or a starting point for a Hengill hike. The detour adds little time if you are going that way anyway, and the view down to the lake from Route 435 is the highlight.

It is not worth a special trip if you expect a visitor centre or a tour of the plant. For that, head to the Hellisheiði power plant on Route 1, where ON Power runs its geothermal exhibition.

How long to spend at Nesjavellir

Allow 15 to 30 minutes for the drive past the plant with a stop at a viewpoint or two. A walk on the Hengill trails can take anything from an hour to a full day, depending on the route you choose from the map.

Photo: Gretar Ívarsson, public domain, via Wikimedia Commons