Lake Hraunhafnarvatn has an area of 3,4 km². It is situated 2 m above sea level and its greatest depth is 3 m. River Hraunhafnara enters it from the south and it is discharged through the narrow gravel reef Hestamol.
Road no. 85 passes along the northern shoreline. The lake abounds in lake char (½-2 pounders) and brown trout (1-4 pounders). The Brown Trout is mainly caught at the mouth of river Hraunhafnara, where the anglers have to walk. The lake is netted.
The distance from the capital is 644 km by the Whale Bay tunnel) and 10 from Raufarhofn.