Hverfjall

Hverfjall is a tephra ring roughly a kilometre wide and about 140 metres high, thrown up in a single explosive eruption around 2,500 years ago when magma met groundwater, and it is one of the more symmetrical craters of its type anywhere. The whole cone is black gravel with almost nothing growing on it, which is why it reads so starkly against the green around Myvatn. Two marked paths climb it, on the north and south sides, and a track runs the full circuit of the rim with the bowl on one side and the lake district on the other. Walking anywhere else on the slopes is prohibited because the scars do not heal.

What you actually see

• A ring a kilometre across - about 140 metres high and strikingly regular.
• Black gravel throughout - almost nothing grows on it.
• A rim circuit - the crater on one side, Myvatn on the other.
• Two permitted paths - north and south, and nothing else.

When to go

May to September; the paths are loose and unpleasant when frozen. Two hours.

Honest expectations

The climb is short but steep on loose scoria that slides underfoot. Wind on the rim is strong and there is no shelter anywhere on the cone. Straying off the two paths is prohibited. No facilities at the car park.

Nearby

Dimmuborgir is next door; Grjotagja and Myvatn are minutes away.