Along the coastline of Sweden and in the huge inland lakes, there are thousands (in fact, hundreds of thousands) of islands and many of them are populated year round. In these areas boats operate in much the same way as buses on the mainland. The service will normally be far more regular over the summer period when Swedes retreat to their summer houses so make sure you have a current timetable. Icebreakers ensure the important routes are still available in winter. If you will be travelling regularly, find out about weekly or monthly cards. There is no one company that operates all the boats and you can find that more than one company will service the same island. Sometime tickets are interchangeable between companies, sometimes not. Check in advance.
If you wish to own your own boat The Swedish Maritime Administration have excellent information available in English. Go in to recreational boating and read about laws and regulations, safety and get good advice for purchasing a boat here.
At this stage it is not necessary to have either a licence or boat registration, although it is only a matter of time before this changes.
With your own boat, the allemansrätt, or The Right Of Public Access, applies – if you’re going to moor, make sure it’s not in somebody’s private land around their house, don’t stay for more than one night and don’t permanently damage the environment.