I have been biking there a couple of times and have always anjoyed Nauvo. Charming little town and conveniently located to further explore the Archipelago.
From Nauvo (or was it Korppoo, which is next to Nauvo) you could take a ferry to Kökar for example.
Some might disagree, but the Archipelago is best explored by a bike :) IMHO you don't need a car. There are buses also, but those I know nothing about.
Thank you, wonderful advice-I will do some research! Do you recommend a particular accommodation in Nauvo?
Besides camping Majatalo Martta is the only place I've stayed there. They seem to get picky reviews on Tripadvisor, which surprises me a bit. They do better on Booking.com.
OK, maybe the room was a bit too romantic for my taste, but it was clean, neat, breakfast was great and I especially loved their morning sauna. It is one of the most special saunas I've been to, but really, really good. For modest ones it had seperate sides for men and women.