When did Brennisteinsfjöll last erupt?

Brennisteinsfjöll last erupted around 1341 AD, producing small lava flows. The volcanic system has been quiet since, but the Reykjanes Peninsula's recent volcanic reawakening has heightened interest in all volcanic systems in the area.

What are the fumaroles at Brennisteinsfjöll?

Fumaroles are vents where volcanic gases and steam escape from the ground. At Brennisteinsfjöll, active fumaroles and solfataras (sulfur-depositing vents) indicate ongoing geothermal activity beneath the surface, producing a distinctive sulfur smell.

Can you hike at Brennisteinsfjöll?

Yes, there are hiking trails in the Brennisteinsfjöll area, accessible from the road between Reykjavik and Hafnarfjörður. The terrain includes old lava fields, moss-covered rock, and geothermal areas. Stay on marked paths near thermal features.

How far is Brennisteinsfjöll from Reykjavik?

Brennisteinsfjöll is approximately 20 km southeast of Reykjavik, making it one of the closest volcanic systems to the capital. The area is accessible year-round via paved roads.

Is Brennisteinsfjöll connected to the Reykjanes eruptions?

Brennisteinsfjöll is one of several volcanic systems on the Reykjanes Peninsula. While the recent eruptions have been at Fagradalsfjall and nearby fissures, scientists monitor all Reykjanes systems as the peninsula enters a new volcanic period.

Brennisteinsfjoll (Brennisteinsfjöll) Volcano Iceland: Geothermal Area Guide

A volcanic system on the Reykjanes Peninsula with active fumaroles and solfataras, just 20 km from Reykjavik—part of the peninsula's geothermally active volcanic belt.

Updated February 1, 2026By the Iceland.org Travel Team

Region

Reykjanes Peninsula

Near Reykjavik. Year-round access.

Brennisteinsfjöll ("Brimstone Mountains") is one of the volcanic systems lining the Reykjanes Peninsula, Iceland's most accessible volcanic region. Though its last eruption was around 1341, the area remains geothermally active with steaming fumaroles and sulfur-depositing solfataras. Its proximity to Reykjavik makes it an easy day trip for those interested in volcanic geology.

Safety + sourcing

Last updated: 2026-02-01

This page is for trip planning, not emergency guidance. Stay on marked paths near geothermal features—ground can be hot and unstable.

Sources to check

Last eruption

~1341 AD

Dormant but geothermally active.

Features

Fumaroles & solfataras

Active steam vents and sulfur deposits.

Distance

~20 km from Reykjavik

One of the closest volcanic systems to the capital.

What to Expect

Volcanic system classification: fissure swarm with multiple eruptive vents along the Reykjanes oblique rift
Last eruption ~1341 AD: small basaltic lava flows; dormant for ~685 years but geothermally active
Part of the Reykjanes volcanic belt now in a new eruptive cycle—Fagradalsfjall eruptions began in 2021 nearby
Active fumaroles and solfataras with bright yellow sulfur deposits and strong sulfurous gas emissions
Moss-covered medieval lava fields from historical eruptions visible along hiking trails
Hiking trails through volcanic terrain accessible year-round from paved roads (~20 km from Reykjavik)
Visitors can observe the contrast between ancient lava flows and active geothermal venting

Nearby Attractions

Blue Lagoon geothermal spa
Kleifarvatn lake
Krýsuvík geothermal area
Fagradalsfjall recent eruption sites
Reykjanes Geopark (UNESCO)
Seltún hot springs and mud pools

How to Get There

Drive Route 42 from Hafnarfjordur or Route 41/Reykjanesbraut toward Keflavik, then turn south
Paved and gravel roads to trailhead areas—no 4WD required; 2WD sufficient year-round
~20 km from central Reykjavik; approximately 25-30 minutes by car
Parking available at signed trailheads near Kleifarvatn lake area and Krysuvik
No guided tour required; self-guided hiking on established trails
Combine with nearby Krysuvik/Seltun geothermal area and Kleifarvatn lake for a half-day trip

Best Time to Visit

Year-round access: roads are maintained in all seasons; geothermal features active regardless of weather
June to August: longest days and warmest temperatures for hiking the volcanic terrain
Geothermal steam and fumaroles are more dramatic in cold weather—winter visits offer striking visuals
Spring (April-May): wildflowers contrast with volcanic landscape; fewer visitors than summer
Combine with Reykjanes Geopark attractions for a full day exploring the peninsula's volcanic systems
Monitor safetravel.is for any volcanic activity updates related to the broader Reykjanes reawakening

Planning help

Brennisteinsfjöll FAQs

Quick answers with safety notes where it matters.

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