The large hollow called Brunahvammskvos contains both the Arnarvatn farm site (420 m above sea level) and, on the Vopnafjörður side of the hollow Arnarvatn lake. This hollow lies below the slopes of Kálffell to the east and Brunahvammsháls and Súlendur to the south. The first farmers at Arnarvatn, from 1867, were Sigurbjörg Sigurðardóttir and Jón Jónsson. The farm was abandoned in 1935. For centuries, Arnarvatn was by the main trail to Vopnafjörður for people coming from Möðrudalur and the northern part of Jökuldalsheiði. Nowadays, one can walk to the ruins from the old road to Vopnafjörður either from the farm Kálffell, which requires crossing a small watercourse next to the farm site, or via a dam at the lower end of the lake. While that route allows for driving to the dam and indeed all the way to the farm. It is worthwhile walking the whole distance, going along the lake to enjoy the tranquility and observe the birds. Drinking water at the spring which is towards the highlands from the ruins is also a nice idea, and there is a shelter used by those rounding up sheep on Hauksstaðaheiði.