Lake Þórisvatn is the second largest lake in Iceland, about 83 km² and its surface fluctuates between 560 – 576 m above sea level. It lies between river Köldukvísl and the Hraunvatna lakes in the highlands of Rangárvallasýsla and its maximum depth is 109 meters. To the south of the lake is a long cape, Útigönguhöfði, which divides it into two bays. Þórisvatn has been the reservoir of Vatnsfells Power station, which is at the southern end of the lake, since 1971. For a long time, the lake was considered fish-free, but good fishing grounds were found there after the middle of the century. Only brown trout are caught and are considered very good. The best fishing in the lake is usually at Austurbotnar and Grasatanga. Also, there is sometimes good fishing at Þórisós.