Small, flat lava shield with a large, 20 to 25 meter deep crater. The shield is at least 9,000 years old. It was formed during a highly effusive lava eruption. The basalt-type is a primitive deep-mantle derived picrite that contains much of the green mineral olivine. Location: The Háleyjarbunga is close to Reykjanes lighthouse on the tip of Reykjanes. A hikingpath is marked form Gunnuhver over the lavafield to Háleyjarbunga.

Háleyjarbunga is a geosite within Reykjanes Unesco Global Geopark.