Vatnajökull National Park is one of three national parks in Iceland. It encompasses all of Vatnajökull glacier and extensive surrounding areas. These include the national parks previously existing at Skaftafell in the southwest and Jökulsárgljúfur in the north.
In general, national parks are protected areas which are considered unique because of their nature or cultural heritage. The unique qualities of Vatnajökull National Park are primarily its great variety of landscape features, created by the combined forces of rivers, glacial ice, and volcanic and geothermal activity.
Vatnajökull is Europe's largest glacier, with a surface area of 8,100 km2. Generally measuring 400–600 m in thickness and at the most 950 m, the glacial ice conceals a number of mountains, valleys and plateaus. It even hides some active central volcanoes, of which Bárðarbunga is the largest and Grímsvötn the most active. While the icecap rises at its highest to over 2,000 m above sea level, the glacier base reaches its lowest point 300 m below sea level. Nowhere in Iceland, with the exception of Mýrdalsjökull glacier, does more precipitation fall or more water drain to the sea than on the south side of Vatnajökull. In fact, so much water is currently stored in Vatnajökull that the Icelandic river with the greatest flow, Ölfusá, would need over 200 years to carry this quantity of water to sea.
The scenery encircling the glacier is extremely varied. Towards the north, the highland plateau is divided by glacial rivers, with powerful flows in summer. The volcanoes of Askja, Kverkfjöll and Snæfell tower over this region, together with the volcanic table mountain Herðubreið. Long ago, huge glacial floods carved out the canyon of Jökulsárgljúfur in the northern reaches of this plateau. The mighty Dettifoss Waterfall still thunders into the upper end of this canyon, while the scenic formations at Hljóðaklettar and the horseshoe-curved cliffs of Ásbyrgi are found farther north.
Broad wetlands and expansive ranges distinguish the areas near the glacier and farther east, around Snæfell. These areas are an important habitat for reindeer and pink-footed geese. The south side of Vatnajökull is characterised by many high, majestic mountain ridges, with outlet glaciers descending between them onto the lowlands. The southernmost part of the glacier envelops the central volcano Öræfajökull and Iceland's highest peak, Hvannadalshnjúkur. Sheltered by the high ice, the vegetated oasis of Skaftafell overlooks the black sands deposited to its west by the river Skeiðará.
These sands are mostly composed of ash which stems from the frequent eruptions at Grímsvötn and is brought to the coast by jökulhlaups, or glacial floods. Substantial volcanic activity also characterises the landscape west of Vatnajökull, where two of the World's greatest fissure and lava eruptions of historical times occurred, at Eldgjá in 934 and Lakagígar 1783-1784. Vonarskarð, northwest of the glacier, is a colourful high-temperature area and a watershed between North and South Iceland.