The islands of Rebbenesøy and Ringvassøy are split, with the southern part belonging to neighboring Tromsø. Ringvassøy island´s highest point, Soltindan, has a height of 1,051 metres, about 14 km southwest of the municipal center of Hansnes. The pretty, nondescript municipal centre is at Hansnes, which can be reached through an undersea tunnel.
Karlsøy is among the world´s most important exporters of dried and salted cod, with Portugal, Spain, and Brazil among the main markets. The population is almost totally dependent on fishing.