Borgarfjörður (Icelandic pronunciation: [ˈpɔrkar̥ˌfjœrðʏr̥]) is a fjord in the west of Iceland near the town of Borgarnes. The waters of Borgarfjörður appear to be calm, however the fjord is on the contrary a rather dangerous part of the sea because of its undercurrents and shallows.
There are many flat islands lying in the fjord, but for the most part they are uninhabited.
Near Borgarnes, the hringvegur (road no.1 or "ring road") passes over a bridge of 0.5 km in length at inland portion of the fjord.
The land around the fjord has been inhabited since the time of Icelandic settlement. Events in the Icelandic sagas such as that of Egill Skallagrímsson are situated here.
The name of the fjord seems to come from the farm of Borg, which according to the sagas was founded by Egill's father Skallagrímur, who took the land around the fjord and accordingly gave the fjord the name of Borgarfjörður.
While serving as a synonym for the various townships, farms, natural attractions and areas in the region, the various inhabitated as well as less populous parts of Borgarfjörður are now generally referred to as Borgarbyggð, a name which in Icelandic denotes its areas of residence and more populated parts and town centers of the region such as Borgarnes, while yet being inclusive of many tourist resorts and attractions as well as the less populated farm and more remote natural areas. Borgarbyggð thus refers to the suburban and populated areas as well as the more rural and less populated areas, while the name Borgafjorður resembles more and describes in detail the actual fjord and surrounding beaches as a natural habitat.