Diameter
1 km
One of the largest tephra ring craters in the world, spanning a full kilometer across
Hverfjall (Hverfell): Tephra Crater near Mývatn
A tephra ring crater a kilometer across rising above Lake Mývatn, among the largest explosion craters of its kind on Earth
Location
North Iceland
Lake Mývatn area, Krafla volcanic system
Quick Answer
Hverfjall is a tephra ring crater about 1 km across near Lake Mývatn, formed in an explosive eruption around 2,500 years ago. Two marked trails climb to the rim.
Hverfjall is a massive tephra ring crater that dominates the eastern skyline of Lake Mývatn in North Iceland. Formed approximately 2,500 years ago in a phreatomagmatic eruption, when rising magma met groundwater, it is one of the largest craters of its kind in the world. The crater measures roughly 1 kilometer in diameter and stands 160 meters above the surrounding lava field. Its dark, symmetrical profile is visible from across the Mývatn basin, and the 20-minute climb to the rim gives 360-degree views of the lake, pseudocraters, lava pillars, and the volcanic highlands beyond.
Sources and page update
Updated: 2026-09-10
Stay on marked trails at all times. The inner crater walls are unstable and steep. Wind can be very strong on the rim. Wear sturdy footwear for the loose tephra trail.
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Age
~2,500 years
Formed in a single massive phreatomagmatic eruption when magma met groundwater
Climb to Rim
~20 min
A moderately steep ascent through loose tephra from the parking area to the crater rim
What to Expect
Panoramic Rim Views
The crater rim has unobstructed 360-degree views of Lake Mývatn, the Dimmuborgir lava formations, Krafla volcano, and the distant highland tablelands.
Sheer Scale
The crater is a full kilometer wide, all of it formed in a single eruption 2,500 years ago. The scale is easiest to grasp from the rim.
Two Climbing Routes
Choose between the shorter, steeper southern trail or the longer, more gradual northern approach. Both are well-marked with cairns.
Full Rim Walk
A 3.2 km path follows the entire crater rim and takes about an hour, with the view changing as you go.
Mývatn Area Attractions
Hverfjall is surrounded by Lake Mývatn's other geological sites, including Dimmuborgir, Grjótagjá cave, and the Skútustaðagígar pseudocraters.
Geological Significance
As one of the world's best-preserved tephra ring craters, Hverfjall is used by geologists as a reference example for this type of volcanic formation.
Getting There
Hverfjall is located on the eastern side of Lake Mývatn in North Iceland. From Reykjahlíð, the main settlement at Mývatn, drive south along Route 848 for approximately 5 km. The signed turnoff for the Hverfjall parking area is on the left side of the road. The parking lot is at the southern base of the crater. From Akureyri, the drive to Mývatn takes about 1 hour east along Route 1. The entire route is on paved or well-maintained gravel roads accessible to all vehicles. The southern trailhead begins directly from the parking area.
Best Time to Visit
Hverfjall can be climbed year-round, but the best months are June through September when the weather is mildest and the trails are free of snow and ice. Summer visits have long daylight hours and green surroundings at Mývatn. The midnight sun period in June and July is a good time for rim walks. Winter visits are possible but require caution, as the tephra trails can be icy and strong winds are more common. Clear days in any season give the best views from the rim, so check the forecast before planning your climb.
Planning help
Hverfjall FAQs
Quick answers with safety notes where it matters.
How difficult is the hike up Hverfjall?
The hike to the rim of Hverfjall is moderately challenging. The trail ascends steeply through loose tephra and gravel, which can make footing difficult. The climb takes approximately 20 minutes from the base. Once on the rim, the walking is easier on a relatively flat path. The full rim walk adds about 1 hour.
Can you walk all the way around the Hverfjall crater rim?
Yes, you can walk the full circumference of the crater rim on a marked trail. The rim walk is approximately 3.2 km and takes about 1 hour to complete. The path has views of Lake Mývatn, the surrounding lava fields, and the highland mountains in every direction.
Which trail should I use to climb Hverfjall?
The northwestern ascent is more gradual; the southern route is steep and more difficult, according to the conservation agency’s Mývatn trail guide. Choose your approach deliberately and stay on the marked trail. Reaching the rim and completing its circuit are separate walks.
Is Hverfjall or Hverfell the correct name?
Both names are used locally. Hverfjall is the traditional Icelandic name, while Hverfell is a more modern variation. Hverfjall translates roughly to 'hot spring mountain' while Hverfell means 'vanishing mountain.' Both refer to the same tephra ring crater, and you will see both names on maps and signage.
For a countrywide view of Iceland’s volcanic systems, explore our Iceland statistics.