Múlaá falls from Skriðuvatn in Suðurdalur, in of Skriðdalur, and is called Grímsá after it and Geitdalsáin converge outside Þingmúli. There are nice brown trout in the river. In the lake, there are both brown trout and char. Fishing in Mulaá does not follow the lake, licenses are specially sold by landowners.