Lake Stora-Eyjavatn has an area of about 1,66 km². Its greatest depth is 43 m and it is situated 569 m above sea level. Its discharge, Thvera, runs through lake Litla-Eyjavatn and thereafter carries the name Dynjandisa.
It takes about two hours to walk to the lake from the main road. A track for 4wd vehicles following the electric masts shortens the walk somewhat. The lake abounds in lake char, 1-2 pounders.
The distance from the capital is about 381 km by the Whale Bay tunnel.