Lake Deildarvatn has an area of 1,3 km². It is rather shallow and situated 38 m above sea level. Its catchment area includes the rivers Fremri-Deildara and Oldua and a few brooks. Its discharge, river Deildara, one of the finest salmon rivers of the Northeast, spills into the sea. The distance from the main road (85) to the lake is 4,5 km and it is accessible by car from the airstrip east of the lake and from the farmstead Holl. The landscape around the lake is boggy. The lake abounds in fish, lake char and brown trout (1-2 pounders). Salmon run through it to enter the upper part of river Deildara.
The distance from the capital is 648 km by the Whale Bay tunnel.