Diameter
1 km
One of the largest tephra ring craters in the world, spanning a full kilometer across
Hverfjall (Hverfell) – Massive Tephra Crater Near Mývatn, Iceland
A colossal tephra ring crater rising above Lake Mývatn, one of the largest and most perfectly formed explosion craters on Earth
Updated February 1, 2026By the Iceland.org Travel Team
Location
North Iceland
Lake Mývatn area, Krafla volcanic system
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 powerful phreatomagmatic eruption when rising magma encountered groundwater, the resulting explosion created one of the largest and best-preserved craters of its kind anywhere 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 its rim rewards hikers with sweeping 360-degree panoramic views of the lake, pseudocraters, lava pillars, and the volcanic highlands beyond.
Safety + sourcing
Last updated: 2026-02-01
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.
Sources to check
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 offers unobstructed 360-degree views of Lake Mývatn, Dimmuborgir lava formations, Krafla volcano, and the distant highland tablelands.
Dramatic Scale
Standing on the rim of this kilometer-wide crater gives a visceral sense of the explosive power that created it in a single eruption 2,500 years ago.
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, taking about an hour and providing constantly changing perspectives of the landscape below.
Mývatn Area Attractions
Hverfjall is surrounded by Lake Mývatn's many geological wonders 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 optimal months are June through September when the weather is mildest and the trails are free of snow and ice. Summer visits benefit from long daylight hours and the vivid green landscape around Mývatn. The midnight sun period in June and July is particularly atmospheric 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 offer the most spectacular views from the rim, so check the forecast before planning your climb.
Planning help
Hverfjall FAQs
Quick answers with safety notes where it matters.