This is great fun, and relaxing. Take a boat from the city center out to the archipelago - an island like Vaxholm.
They are old, restored steamers and a real treat. You can usually get a beer and sandwich on board.
Takes an hour to 75 minutes each way.
Spend some time on an island, then get the boat back. You have a good choice of restaurants & cafes by the harbour, and you can visit the castle (another very short - 200m - boat trip across the bay).
It all gives you a real sense of how the city is a maritime place.
75 SEK each way in June 2010. You can eat on board - a sit down meal or sandwich & a beer.
You can also take "tourist" excursions - lunch or dinner cruises.
Bring something warm to wear even in good summer weather. It can be chilly, and the weather can change.
Vaxholm is the most famous island of the Stockholm Archipelago. It has only one village, surprisingly also called Vaxholm, which is the capital of the archipelago.
The village of Vaxholm has a beautiful centre with all wooden houses in a nice range of colours. Throughout the centuries there only have been built wooden houses, unless the fact that this is a huge risk in case of fires. Luckily this never happened. Today it is a popular destination for daytrips from Stockholm. Because it belongs to the inner part of Skargarden, it is easy to reach, even by bus.
Right next to the main island there is a nice fortress. During the 17th and the 18th century this building resisted attacks by the Russians and the Danish successfully. Today you can visit the fortress to see the prison inside and the war museum.
On the island you should just have a nice walk to see the many beautiful summer houses. Green houses, yellow houses, pink houses and the nicest flowers. There are several tiny harbours, and the main harbour has some nice cafes, restaurants and shops.
From Vaxholm all the boats towards the other islands, further in the archipelago depart.