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.
From times immemorial salmon and trout have been caught with various tools in the fjord and the streams here. Finds in the Stone Age settlements at Skipshelleren indicate that salmon was probably caught by angling. Nets, fish pots and traps have been used in the rivers right up to our times. In the fjords the use of nets was developed into a salmon seine around 1500, and later into what today is known as fixed seine.