It originates in the northwest corner of Hofsjökull and is formed from many branches that fall together and flow northward.

[1] The beginning of the river runs through relatively low-pitched and level land, through a deep canyon, called Þröngagil.

It then follows the length of a valley finally falling into Vesturdalur to the northeast, where Hofsá (“Temple river”) flows into it.

Hofsá runs briefly along Vesturdalur, before joining the Austari-Jökulsá at Tunguháll, at which point the rivers are known as the Héraðsvötn.

[3][4] White-water rafting is available on both the Vestari- and Austari-Jökulsá, which are considered particularly well suited to this activity.