About the Area

Nesjavellir sits on the northern slope of the Hengill volcanic massif, a 100 km² geothermal area that last erupted about 2,000 years ago. The lava from that eruption — the Nesjahraun field, fed by a 30 km fissure system — is still visible across the landscape. Today the area is one of Iceland's most powerful geothermal zones, and the Nesjavellir Geothermal Power Plant (run by ON Power) sits in the middle of it, supplying hot water and electricity to Reykjavík.

From the trailhead viewing platform you look down onto the silvery roofs of the power plant, the steam rising from the earth around it, and the deep blue of Þingvallavatn beyond. The hike heads off from there into a landscape that genuinely doesn't look like anywhere else on the Golden Circle — every shade of brown, yellow, orange and brick-red, with vivid blue pools and white silica deposits in between.

Four Routes from One Trailhead

The Nesjavellir trailhead is a choose-your-own-adventure: pick the route that fits the time you have.

• 1) Short out-and-back (~40 min): Park at the southernmost lot, walk a few hundred metres into the most colourful section and back. Perfect when you're short on time.
• 2) Nesjalaugar + Köldulaugar loop (~6 km, 2–3 h): The classic route — descends a closed gravel road for ~15 minutes, then loops through both geothermal areas. This is the sweet spot for most visitors.
• 3) Nesjavallahringur via Hengill (~6.6 km loop, ~2.5 h): A moderate ring trail that adds a section of the Hengill ridge for wider views over Þingvallavatn.
• 4) Hengill summit — Vörðuskeggi (~12 km RT, 5–5.5 h, ~700 m elevation gain): The full ascent of the volcano for fit hikers. A serious mountain day.

What You See

On the classic Nesjalaugar–Köldulaugar route you pass:

• Nesjalaugar — a cluster of warm pools and a cave from which an underground hot spring hisses and bubbles.
• Köldulaugar ("Cold Pools" — actually fumaroles and mud springs, ironically named) with bright sulfur yellow, iron red, and silica white deposits.
• A bridge over a hot, steaming river near the far end of the loop.
• Small craters, lava fissures, and patches of blue, pink and orange lava rock.
• Steam venting straight out of the hillsides — sometimes with tiny white butterflies flitting through it on warm days.
• Sweeping views over Þingvallavatn, Iceland's largest natural lake.

Folklore

The mountain Dyrafjöll, just east of the trailhead, is the home of the giantess Jóra in Icelandic folklore. And in nearby Botnadalur valley there is said to be an elf church — with documented sightings as recent as 1938. Iceland.

From Northern Lights Cabin

• Distance: ~50 km
• Drive time: ~45–55 minutes
• Route: Head north on Þingvallavegur (Route 36) past Þingvellir National Park, then turn onto Nesjavallavegur (Route 435) which curves around the northwest shore of Þingvallavatn down to the geothermal area.
• Parking: Park at the viewing platform overlooking the lake and the Nesjavellir geothermal power plant. There is a smaller southern lot for the short taster walk.
• Trailhead: The route descends a closed gravel service road for about 15 minutes before reaching the first geothermal features.

Good to Know

• Stay on marked paths. Geothermal crust can be only millimetres thick — people have been severely burned by stepping off-trail. Poles and sticks mark the safe route.
• Wear sturdy hiking boots — the rocky path through Köldulaugagil gorge has loose stones and small creek crossings.
• The smell of sulfur (hydrogen sulfide) is strong in places. It's harmless in the open air but can be unpleasant — bring a buff or scarf if you're sensitive.
• Bring layers and a windproof shell — the trail is exposed and the lake winds can be cold even on warm days.
• Carry water and snacks. There are no services on the trail itself.
• Best season is late May through October. In winter the markers can be buried under snow.
• Combine with a visit to Þingvellir National Park on the same day — the drive passes right through it.
• Always check the forecast at vedur.is before heading out.