Tyssøyna or Tyssøy is an island in Sund municipality in Hordaland county, Norway. The island lies in the northern part of the Raunefjorden. The island has a population of about 60 and it is connected to the neighboring island of Bjorøy to the north via a short bridge. Bjorøy is connected to the mainland by the Bjorøy Tunnel. The island is named for the Norse god Týr.