Lambholmen consists of sandstone from the Devonian period, with some layers rich in fossils. This site is the only known fossil-bearing locality in the Solund and Værlandet/Bulandet basin, and it is a key site for dating the Devonian deposits. The island is an important nesting area for birds, and access is therefore restricted. Landing is prohibited between 1 April and 1 August. Access to Lambholmen requires a boat.
