At 400–500 m Interior Highlands are where man has never made his home and is still a rare visitor and for centuries, the interior of Iceland was virtually inaccessible, playing host only to outlaws in hiding. Mostly an uninhabitable volcanic desert in a surface of grey, black or brown earth, lava and volcanic ashes, The highlands are nature is still at its rawest, an untamed mingling of rocky deserts, jagged peaks, volcanoes, ice caps, valleys, steaming hot springs with glaciers, deserts of black sand, barren glacial moraine, active and extinct volcanoes and strange oases of vegetation. Highland favorites include the area around Mt. Askja, where you can bathe in a naturally warm lake called Viti (Hell), and Kverkfjoll high-temperature geothermal field on the rim of Vatnajokull. Surrounded by obsidian and colorful rhyolite mountains visitors can bathe in natural hot rivers in the geothermal area of Landmannalaugar, and Laugavegur trail leads to the woodland nature reserve Þórsmörk, a hidden valley surrounded by mountains, glaciers and glacial rivers. Overland routes Kjolur and Sprengisandur link the north and south and Kjolur is passable by ordinary vehicles in summer, skirting Langjokull glacier on the way to Hveravellir geothermal field before emerging by the Ring Road in the north. Sprengisandur route consists of rough tracks trails and un-bridged rivers that can only be negotiated by big 4WD vehicles, a difficult route that threads its way between glaciers to come out southeast of Akureyri, near Lake Myvatn.