Heiðarvatn is about 1.9 km² in area and lies about 70 meters above sea level. It has been measured at a depth of about 30 meters, but the average depth is about 13 meters. This lake has for years been one of the most popular and well-known lakes in the country, where you can catch almost all types of Icelandic freshwater fish, i.e., sea trout, brown trout, Arctic char, and occasionally salmon. Much of the fish in Heiðarvatn is small char, but the sea trout can be up to 13 ~ 14 pounds. It is therefore advisable to have strong leaders when baiting for sea trout and brown trout, not to mention the salmon that have broken many trout lines. From Heiðarvatn, Vatnsá flows into Kerlingardalsá.