Lómagnúpur are 688 m high palisades that tower south of Björn, west of Núpsvötn on Skeiðarársandur. West of Lómagnúpur is the farm Núpsstaður. The spectacular surroundings of Núpsstaður and Lómagnúpur are well known. The area reaches from the ocean and black sands and all the way to Vatnajökull. Volcanic eruptions, glaciers and lakes have shaped the environment there, in addition to shaping diverse formations.
At Núpsstaður there are remarkable old buildings that are believed to be typical for farms in Iceland in past centuries. The most noteworthy of these is the chapel, one of few remaining turf churches in the country. It is believed that the chapel is mostly from a church that was built around 1650. Church was abandoned there in 1765, though religious observance was never quite abandoned, but the chapel was used as an outhouse for a while. In 1930 the chapel was proclaimed inviolate, and in 1961 it was re-consecrated.
In the latter part of the 18th century a rock slide fell from the western part of Lómagnúpur, and the marks can be seen from the main road. In Sveinn Pálsson's diary it reads: "This happened on the morning of a day in July, so suddenly that a girl that was carrying milk home to Núpsstaður heard a crack, like a crash of thunder, and immediately looked to Lómagnúpur, but couldn't make anything out at first due to dust. But she had only barely put down her milk buckets, to look closer, when it was all over and the rock slide lay on the sands, where it now is, up to a quarter of a mile from the mountain, in small piles with deep hollows in between, or funnel-shaped whirlpools, that have likely been created due to compression of air." This rock slide was followed by a flood of water that probably caused the rock slide. More recent signs can be seen in the eastern slopes of Lómagnúpur, where a rock slide fell in 1998. As with other palisades along the southern coast of Iceland, the sea reached Lómagnúpur during ice age. Lómagnúpur are very graceful and beautiful.
Lómagnúpur is mentioned in Brennu-Njáls saga, in a rather peculiar role, where it appears in the dream of Flosi Þórðarson at Svínafell, but Flosi was the deviser of setting fire to Njáll Bergþórsson's farm. Flosi dreamed that he was at a farm by Lómagnúpur, he walks out and looks to the mountain. The mountain opens up and a giant clothed in goatskin and with an iron rod in hand steps out. He recites the names of the 25 men that plan to burn down Njáll Bergþórsson farm. He then bangs his rod against the ground and steps back into the mountain. All of the men that the giant names are later killed in revenge for burning down Njáll's house.
The giant of Lómagnúpur can be seen on Iceland's coat of arms. It is one of Iceland's four guardian spirits, and guards the south coast from evil forces. All of Núpsstaður land is listed as natural remnants.