Oksøy, at the entrance to Kristiansandsfjorden, is the eastern point of the Oksøy-Ryvingen protected landscape, where ten seabird reserves stretch westwards towards Ryvingen near Mandal. Lesser Black-backed Gull, European Herring Gull and Common Tern breed in large numbers alongside Common Eider and Eurasian Oystercatcher, and a large proportion of Norway's Lesser Black-backed Gull population breeds in the area. The 36-metre cast-iron lighthouse from 1900 is a landmark at the mouth of the fjord.