Not amazingly, many people here have a boat. So did my family when I was a child. We had a rather small motorboat, and my family and other kindred would all gather at the Maisaari island. My brother has a motorboat, and many of my friends have had one, or a sailboat. I kind of like sailboats, so I may get myself one some day.
The number of islands is so high that even though thousands of people go out there every summer weekend, everyone can always get their own island to stay in, if they like. Some of the islands are just small treeless rocks, but most have some forest.
Nevertheless, most of us who live here take the archipelago for granted, and rarely even think about it. So have I for most of my life. I kind of rediscovered it last year when I got into paddling. A kayak is really very useful for exploring the archipelago, as you can get everywhere with it. Many parts of the archipelago are unreachable by motorboats or sailboats, as they are too shallow and have too many underwater rocks, but with a kayak or canoe you can get everywhere. It is a bit slow and requires some effort, but on the plus side, it keeps you in shape. Not surprisingly, kayaking and canoeing have become really popular in Finland, and especially so in the Turku area.
I started kayaking mostly last year, and after some trips with rented kayaks, I got myself one. So far, most of my trips have been just daytrips or one-night trips, and one two-night trip for a weekend. But why stay longer, as you can always go next weekend as well.
A private boat is by no way the only way to explore the archipelago. There are many "water buses" that go to some islands daily, and bigger ferries to the more remote islands. Most of these ferries, especially to the most remote islands, are actually totally free of charge. The ferries go also in the winter, pushing through ice. There's also an Archipelago Route, which you can go by car or bicycle, with free ferries between the islands.
Oh, Finland also has 187 888 lakes (larger than an acre). The number of lakes by the land area is also probably the highest or among the highest in the world.