Self-service cabin on an island in the Oslo Fjord. Must be booked and payed in advance - see the website for more information.
You can book on the web or by contacting the Oslofjord Outdoor Recreation Council (OF) by phone on +47 67 55 49 90.

The former lighthouse keeper's cottage has been refurbished for overnight stays and has 8 bunk beds divided among three bedrooms, plus an unfurnished boathouse with six foldaway beds. The two rowboats used to get to the island are stationed at Alværn pier.