Furthest north in the island community Rongevær, at the entrance to Fensfjorden, lies Krossøy. Belonging to the farm are the islands of Krossøy, Husøy, Kårøy, Lyngkjerringa, Søre Kjerringa, Rotøy and Kuhovet. All of them have been inhabited. On Krossøy itself today there are four holdings. The marine use environment here is one of the best preserved along the West Norwegian coast.
Around Mjøsvågen here is still a compact marine use area. Some of the buildings are common boathouses, but most of them also house small enterprises and workshops. This is where the farmers from Øvsthus, Mjøs, Hole and other farms have supplemented their meagre incomes as smiths, brass moulders, clog makers, chest builders and decorative painters.