Keilir

Keilir is a cone, and an unusually regular one. The shape came from a fissure eruption under the ice of the Pleistocene, which narrowed at the end to a single vent. The eruption melted a lake into the glacier. Water reached the magma, the explosions threw out tephra, and the tephra settled through that lake in layers until a mountain covered the vent. The rock is móberg, a mafic lapilli tuff. A small cap of lava sits on the summit, and it is not settled whether that makes Keilir a tuya or a plugged vent. The same eruption left a scatter of low hills to the north. Because the cone can be picked out from Reykjavík and from the sea, fishermen and seamen steered by it for centuries.

• No phone reception — coverage is bad or absent across the whole area. Set up maps and make any calls before you drive in.
• Fully exposed — the hiking route is very exposed to weather and wind along its whole length. Bring a windproof layer.
• Two stages, not one — getting from the car park to the foot of the mountain is a walk in its own right, before the climb starts.

Access is by car. From the highway a gravel road runs about 8 km in towards the mountain, and it is rough going. It ends at a car park, and Keilir is still some way off on foot from there — the walk in comes first, the climb after. The trail up the mountain starts on the east-north-east side.

Best: clear, dry weather with good visibility. Avoid: low cloud, fog, and days when the ground is icy.

The climb is worth it for one thing, the view, and the view exists only in clear air. From the top you see much of the Reykjanes Peninsula and Faxaflói. Inside a cloud there is nothing to look at, and the loose upper slope is harder work. Check the forecast for wind as well as rain: there is no shelter on the route.