Two of the best birding sites in the outer Oslo fjord area are the shallow bays Ilene and Presterødkilen, situated on either side of Tønsberg town. Ilene on the west side is the delta of Aulielva river, surrounded by farmland and sheltered from the sea by Nøtterøy island. Presterødkilen has large areas of exposed mud at low tide and is lined by dense reed beds, but the surroundings beyond that are urban-industrial and not very bird friendly.