Borgarfjörður is home to my favorite waterfalls in Iceland, Hraunfossar. Here is also where you'd find the biggest lava cave in Iceland, one of the biggest in the world. The most productive hot spring in Iceland provides hot water for countless green houses and hot pools. A fine way to end a day in Borgarfjörður would be the hot tubs at Krauma spa.
8 to 10 hours.