Grímsá rises near Reyðarvatn and runs some thirty-two kilometres down Lundarreykjardalur to join the great Hvítá system in Borgarfjörður, the most prolific salmon country in west Iceland and barely an hour from Reykjavík. A medium river by Icelandic measure, it carries around sixty named pools over volcanic rock, the most famous being the Laxfoss, where the water tips over a ledge beneath the lodge cliff and holds taking fish through the season. The character is classic Borgarfjörður: clear freestone glides and ledge pools on a moderate gradient, double-bank water shared by only eight rods so each has room. It is a river with tradition worn into it, fished by visiting anglers since the late nineteenth century. Wading is straightforward on firm volcanic gravel, with care needed on the smooth rock around the falls.

Wading: Smooth rock around the Laxfoss ledge