Eldborg is by far the highest of five craters lying along a volcanic fissure in the slopes of Geitafell, and is often called Stóra-Eldborg (Big-Eldborg). It is steep and made of scoria and spatter. A prominent lava channel branches off to the east. Both Stóra-Eldborg and Litla-Eldborg (Small-Eldborg) are protected. It is possible to hike up to Stóra-Eldborg, which is by many considered the most beautiful crater in the Southwest of Iceland, and from there to Litla-Eldborg where one can look straight down the crater.

Near Grindavík south of road 427 is Stóra-Eldborg and below the road is Litla-Eldborg. The path to Stóra-Eldborg was recently fixed and a new parking lot was built.