Gíslholtsvötn are in Holtshreppur, a short distance east of Þjórsá. There are two lakes in the area, the East and the West. Eystra Gíslholtsvatn is about 1.6 km² in area and at 65m above sea level. The maximum depth is about 8 m and the average depth about 2.5 m. There is a considerable amount of fish in the lake, some brown trout but especially char. The char is quite small but the brown trout can be rather big. Many who have cultivated the lake have achieved great success. There is a fairly even catch in the lake during the summer, but the brown trout usually bite/take particularly well in the first half of the summer.