Hamre Church has, by all accounts been one of the four main churches in Horda County in the Middle Ages. Hamre was a main church for the whole of Hordaland. Timber remains in the present church show that there was a stave church here in medieval times.
In the sunny, steep fjord landscape along Sørfjorden on the east side of Osterøy is the farm Havrå. The small “hamlet” is one of the few undisturbed farming communities that gives us the impression of the large communal yards in West Norway in the 1700s, with houses built close together and strips of arable land.
Herlandsnesjane, a four-kilometre long peninsula in Lake Storavatnet in the middle of Osterøy, is well known among botanists. Here lies an unusually large and diverse bog.
On Christmas Day 1795, at 5 a.m., the lightning struck the church in Hosanger. After three hours, the timbered church from the 1600s, which had replaced the stave church from the Middle Ages, was in ashes. Already on New Years Day in 1796, a sermon was held for the Hosanger population in the main church at Hamre, to which the congregation belonged earlier,
Large quantities of nickel ore have been mined from Litlandsvatnet, between Lonevågen and Hosanger. The discovery was made in 1875. During the period of operation from 1882 to 1945, 4170 tonnes of pure nickel were extracted from 462 000 tonnes of ore, a large production by Norwegian standards.
It is said that the salmon populations with the largest and the smallest salmon in the world both come from the waters that run out into the fjord system around Osterøy. Vosso is supposed to have the largest spawning salmon to be found in any river, whereas Lonelva is said to have the smallest.