The mountain massif Kerlingarfjöll (The Giantess Mountains; 800 - 1500 m) is the main ornament in the chain of mountains and glaciers framing the Kjölur area. It covers about 150 km² area southeast of the Temple Glacier (Hofsjökull) close to the Keldur Road. The area is full of small steaming hot springs, mud pools and water fountains. It is truly a hiker's paradise. It is one of the largest geothermal areas in all of Europe. It derives its name from a single, 25m high and dark hyaloclastite pillar protruding from the light colored, rhyolite scree of the peak Kerlingartindur. The aforementioned types of rock represent the main structure of the mountain massif and this yellowish tint is the dominant color in the area.