Is Grensdalur extinct?

Yes, Grensdalur is considered an extinct volcano. It has not erupted in thousands of years, and its volcanic activity has been replaced by geothermal features in the surrounding area, particularly near Hveragerði.

Can you hike at Grensdalur?

Yes, Grensdalur has good hiking trails accessible from Hveragerði. The trails pass through varied terrain including geothermal areas, green valleys, and volcanic formations. The area is suitable for day hikes of various lengths.

What geothermal features are near Grensdalur?

The Grensdalur area near Hveragerði is rich in geothermal activity, including hot springs, steam vents, and the famous Reykjadalur hot spring river where you can bathe in a naturally heated river.

How do you get to Grensdalur?

Grensdalur is easily accessible from Hveragerði, which is about 45 minutes from Reykjavik on Route 1. Hiking trails start from the town and lead into the Grensdalur valley. No 4x4 is required.

When is the best time to visit Grensdalur?

Summer (June–August) offers the best conditions with longer days and accessible trails. However, the area can be visited year-round as it is close to the Ring Road and at low elevation. Winter visits may have icy trails.

Grensdalur Volcano: Geothermal Hiking near Hveragerði

An extinct volcano near Hveragerði with hiking trails through geothermal terrain, one of the most accessible volcanic areas from Reykjavik.

Last reviewed March 3, 2026By the Iceland.org travel deskEditorial policy

Region

South Iceland

Near Hveragerði. Easy access year-round.

Grensdalur is an extinct volcanic system near the geothermal town of Hveragerði, just 45 minutes from Reykjavik. While the volcano itself is no longer active, the area is rich with geothermal features: hot springs, steam vents, and the Reykjadalur hot river. The hiking trails here pass through a landscape shaped by both ancient volcanic activity and ongoing geothermal processes.

Sources and last reviewed

Last reviewed: 2026-03-03

This page is for trip planning, not emergency guidance. Stay on marked trails near geothermal areas. Ground can be hot and unstable.

Pages are reviewed for practical usefulness, source quality, and volatile claims before publication.

Official sources to check

Status

Extinct

No eruptions in thousands of years.

Best for

Hiking + geothermal

Trails with hot springs and steam vents.

Distance

~45 min from Reykjavik

Via Route 1 to Hveragerði.

What to Expect

Extinct central volcano classification: part of an ancient volcanic system that ceased erupting thousands of years ago
Now characterized by residual geothermal activity: hot springs, steam vents, and altered clay deposits
Reykjadalur hot spring river: 3 km hike from Hveragerdi to a natural warm river for bathing (year-round)
The 2008 magnitude 6.3 South Iceland earthquake created new hot springs and altered geothermal features visibly
Well-marked hiking trails from Hveragerdi through green valleys with volcanic rock formations and hot springs
Colorful geothermal clay deposits: reds, yellows, and whites from mineral alteration by volcanic gases
Geological features include ancient lava flows, hyaloclastite formations, and eroded volcanic plugs

Nearby Attractions

Hveragerði geothermal greenhouses
Selfoss town and services
Golden Circle day trip route
Kerið volcanic crater lake
Þingvellir National Park (UNESCO)
Ölfusá river (Iceland's largest by volume)

How to Get There

Drive Route 1 to Hveragerdi (~45 km from Reykjavik, approximately 40 minutes)
Hiking trailheads for Reykjadalur and Grensdalur valley are signed from central Hveragerdi
No 4WD required: paved road all the way; parking at trailheads is free
Reykjadalur hot river hike: 3 km each way (6 km round trip, 2-3 hours total including bathing)
Public bus service (Straeто Route 51) runs from Reykjavik to Hveragerdi; trailhead is walkable from bus stop
One of the most accessible volcanic/geothermal hiking areas in Iceland; no guide required

Best Time to Visit

Year-round access: trails are at low elevation and accessible in all seasons
June to August: warmest months, longest days, best conditions for Reykjadalur river bathing
Winter: trails may be icy, so bring microspikes; the hot river can still be used for bathing
Spring (April-May): wildflowers begin to appear; trail less crowded than summer
Weekday mornings are least crowded at Reykjadalur; summer weekends can be very busy
Geothermal steam is more visible in cold weather

Planning help

Grensdalur FAQs

Quick answers with safety notes where it matters.

All volcanoes