Lake Oddastadavatn has an area of about 2,52 kmē, it greatest depth is 18 m and it is located 57 m above mean sea level. It is almost round in shape and rather indented with coves. The river Hraunholtsa enters it from lake Hlidarvatn and its discharge is the great Salmon river Haffjardarda. Two small islands lying close to one another decorate the lake.

The mainstay of the catch is nice lake char, but some brown trout is caught as well. Nets are also used in the lake.
The distance from the capital is 125 km by the Whale Bay tunnel and 51 km from Borgarnes.