If you are cunning enough to decipher the timetables and well organized enough to take enough provisions with you to survive on an island for a few days, then we can share our top camping picks with you.
Berghamn and Jurmo are both easily accessible by ferry and have an authentic rustic charm. Both have free National Park camping spots and are accessible on the Utö ferry route which departs from Pärnäs. Pärnäs is connected to Turku with a frequent bus service, many departures and arrivals are meet the ferry, these are marked on the ferry timetable in yellow with a #. There are even direct buses from Helsinki, Thursdays, Fridays and Sundays during the summer. Pärnäs has free parking, although this can be busy during the summer.
Bus timetables: www.matkahuolto.fi
Ferry timetables: https://meritie.fi/aikataulut/