Hvítá (Icelandic [ˈkʰviːtˌauː], "white river") is a river in Iceland that begins at the Hvítárvatn glacier lake on the Langjökull glacier in the highlands of Iceland at Coordinates: . The river flows for 40 kilometres (25 mi) before dropping down into a narrow gorge at the Gullfoss waterfall.
After this, the river flows between the Biskupstungur and Hrunamannahreppur districts. Here, the Hvítá combines with three other rivers: the Tungufljót, the Brúará, and the Stóra-Laxá, doubling the volume of the river. It proceeds to run through the flatlands near Grímsness and behind Ingólfsfjall mountain. Just north of the town of Selfoss it meets the Sog River where it becomes the Ölfusá as it flows into the Atlantic Ocean.
Because of the danger of flooding, especially in the winter, it has the reputation of being the most dangerous river in Iceland.
Organised rafting excursions take place on parts of the river.