Urriðafoss is a waterfall located in the river Þjórsá in southwest Iceland. With a flow rate of 360 m³/s, it has the highest average water flow of any waterfall in Iceland, and the second highest in Europe behind the Rheinfall. The Fossafélagið Títan company was given permission in 1927 to build a power plant in Urriðafoss in connection with a railway to Reykjavík from the waterfall.