This is one of the largest alluvial plains of the country. It is situated between the counties Oraefi and Fljotshverfi and has an area of approx. 1000 kmē. The distance between the glacier's edge and the sea is between 20 and 30 km and its coastline is 40 km long. A few glacial rivers form innumerable branches in the lower regions and sometimes-terrible flood waves occur, especially when the sub glacial caldera Grimsvotn empties or sub glacial eruptions take place. This plain is mostly devoid of vegetation. Driftwood was sought on the beaches in spite of the distance down there, the rivers, and the quagmires. It was much easier to ride down there during winter, when everything was frozen. Much less driftwood is brought to the south coast by the Gulf Stream nowadays from South-, Middle- and North America.

The common grey seals and the harbour seals have their rookeries in several places along the beach, where the farmers hunted them. The eastern edge of the outwash plain was inhabited in the past, when there were fewer floods and more vegetation. The oldest sources describing such flood waves date back to 1598. They have become much smaller during the last few decades than during the early part of the 20th century. The flood wave, caused by the sub glacial eruption in 1996, was extraordinarily big. It peaked with about 55.000 cubic metres per second and the total discharge is estimated to have been about 3,5 cubic kilometres.

Doubtless, the glacier and outwash plain areas were a big bay in the past, because up to this date trunks and branches of trees are carried with the melt water from underneath the ice. Before the bridges were built, the rivers were great obstacles, except during the coldest part of winter, and it is astounding, how few lives were lost during travels there in the past. Most lives were lost, when ships ran aground, and the shipwrecked had to seek shelter in bad weather conditions.

On The 19th of September 1667, a Dutch merchantman, Het Wapen van Amsterdam, ran aground. It was a large ship with about 150 crew and a few passengers. This vessel was used for journeys between India and The Netherlands and must have drifted all the way up here in bad weather. The shipwrecked encountered very bad weather on the outwash plain, 140 of them died and 60 were rescued. The cargo of the ship was very precious and the wreck has been sought for almost 40 years now.