Boat to the islands: Oslo Ferries
The Oslo Ferries take you from the city centre to the islands of the Oslo Fjord. Tickets for public transport are valid on the ferries.
The ferry boats from Rådhusbrygge 4 (City Hall Pier 4) take you to the islands of the inner Oslo Fjord.
Line B1: Hovedøya > Bleikøya > Gressholmen > Lindøya øst > Lindøya vest > Nakholmen > Hovedøya (all year)
Line B2: Hovedøya > Lindøya vest > Nakholmen > Hovedøya (June-August)
In summer the ferries operate from early morning until late at night; in winter there are only 7-8 departures per day.
Tickets
All Ruter tickets (tickets for public transport in Oslo) are valid on the ferries. Tickets are not sold on the islands, so buy your tickets in advance or use Ruter's mobile ticket app.
Source: VisitOSLO as
Boat to the islands: Oslo Ferries