Summary[edit] Description: English: Two great black-backed gulls (Larus marinus) on a rock by Hannevikeholmen in Hanneviken, a part of Trommekilen, Norrkila, Lysekil Municipality, Sweden. Date: 29 April 2018, 18:25:08. Source: Own work. Author: W.carter. Camera location58° 20′ 57.9″ N, 11° 27′ 30.44″ EView all coordinates using: OpenStreetMap 58.349418; 11.458456.