The Grimsa is a medium-sized river in the midwest region of Borgarfjordur, which is Iceland's most prolific Salmon area. Often referred to as “The Queen of Rivers”, it is an important and impressive river.

Not only is Grimsa one of Iceland's most beautiful fly fishing rivers, it is also one of a few Icelandic rivers that has tradition stamped all over it. It was frequented by British lords and an assortment of high ranking military personnel as early as the late nineteenth century and whilst as with most of Iceland's rivers today, it is primarily a grilse river. During those early days the river was famous for its huge specimen salmon. Every now and then, the odd monster is still spotted giving vivid memory of the golden days of yesteryear.

As on many Icelandic rivers, floating lines, small fly patterns and hitched tubes are excellent. The river is also easily fished with single-handed rods, although given that Iceland is often windy, a double-handed rod should be available as well.

The river is fly only water with a voluntary and widely practiced catch and release system. Any given season a normal catch on the eight daily rods is somewhere between 1,200 to 1,800 fish. The Grimsa also has a decent run of sea trout that often starts in early July.

The Grimsa Lodge is not like any other lodge in Iceland. It stands out stark against the sky, nestling on a cliff above the main falls were you can watch the leaping Salmon from both the main dining room and the lounge. The building was designed by Ernst Schwiebert, the well known American architect who used to fish Grimsa regularly.