Osmussaar is unique for its interesting nature and history. The island was first inhabited by the Estonian Swedes; after the WWII, Osmussaar became a restricted border zone with a military base of the Soviet army. The island is 4.8 kilometres long and 1.6 kilometres wide. Its highest spot is 8 metres high. Osmussaare probably rose from the sea 3000 years ago. The landscape is characteristic for its limestone shore, breccia boulders, vast shingle mould areas and juniper shrubland.
The island has a 9 km RMK hiking trail with campfire sites. A striped reinforced concrete lighthouse that can be admired from the outside stands on the limestone shore in the north-western part of the island.