Keilir is a hyaloclastite conical mountain located on the Reykjanes peninsula not far from the Keflavík International airport. The mountain is about 379 meters high, formed in a volcanic eruption under ice during the ice age. Keilir is popular among hikers as it provides great view over the peninsula from the top. The hike is not to hard and takes about 2-3 hours.
From Reykjavík take the Reykjanesbraut (41) and turn off the road where the sign says Keilir, towards Vatnsleysustrandarvegur road. Take the road towards Höskuldarvellir and park the car. From there it is a clear footpath to the mountain.