As early as 1857 a German firm obtained permission to build a guano factory on Finnholmen. Guano is based on dried cod heads, a valuable commodity for fertilizing both farmland and domestic gardens, The Guano factory provided a small industry, who’s odour competed with the drying cod fisheries. The area became too small and a new factory was built on Sauøya. In 1888 Rønneberg & Sons bought Finnholmen and established a fish factory here, producing both salted and dried fish. The original buildings burned down in 1921, and bigger and more suitable buildings were built.
Alf R. Johansen took over Finnholmen in 1970. A freezer was added in 1972 and in 2000 the two uppermost floors that had been the fish salting area were reconstructed into tourist accommodation.