The Highlands of Iceland cover most of the spectacular interior of Iceland. They are situated above 400–500 meters and are mostly an uninhabitable volcanic desert, because the water precipitating as rain or snow infiltrates so quickly into the ground that it is unavailable for plant growth, which results largely in a surface of grey, black or brown earth, lava and volcanic ashes. A few oasis-like areas, such as Herðubreiðarlindir near Askja, are found only in proximity to rivers.
This part of Iceland is not accessible for most of the year, its roads are closed off and impassable during the winter and into the early weeks of summer.  They are also quite difficult to cross during the best of times and visitors to Iceland should definitely not attempt to drive rental cars in the highlands.

Icelanders categorize the Highlands as:
"Háls", meaning a broad mountain ridge between valleys, such as the one near Langavatn north of Borgarnes; or
"Heiði", meaning the real highlands, such as those alongside the Sprengisandur road.

Most of the numerous Icelandic glaciers, such as Vatnajökull, Langjökull and Hofsjökull, are also part of the Icelandic Highlands. Vegetation is only found on the shores of the Glacier Rivers. Where there is also the danger of glacier runs.
Some of the most interesting parts of Iceland with volcanic activity are to be found in the Highlands, such as Landmannalaugar and the region around Askja and Herðubreið.