Renting Kayaks in Stockholm
(EDIT: click here for a more recent reposting with updated information and links). Stockholm isn't called the Venice of the North for nothing! Central Stockholm alone is built on about 15 islands, so there is water everywhere. One fun activity to do on a sunny afternoon is to rent a kayak and paddle around the islands. Stockholm is at her most beautiful when seen from the water! Kayaking is fun and you don't need to be an Olympian to do it... good as a family outing. There are several places to rent kayaks by the hour/day and it is generally quite inexpensive. Depending on the place, you are looking at about 100 SEK an hour though it is sometimes cheaper if you take the kayak for half or full day.
When choosing a kayak rental place think about where you want to paddle! Stockholm actually strides the borderline between a lake and the ocean with the Old Town being the borderline. Everything to the east is the Baltic Sea and everything to the west is Lake Mälaren. If you want to paddle in the lake then I recommend Kafé Kajak located in Rålambshovs Park on the island of Kungsholmen. Or else you can head across the bridge to the island of Långholmen where you will find Långholmen Kajak. Here you will be able to paddle by a lot of parklands and beaches as well as cliffs where Stockholmers enjoy diving and sunbathing. If you want to paddle in the Baltic Sea area, then I recommend Djurgårdens Sjöcafé located on near the bridge leading from Östermalm over to the island of Djurgården.
Stay close to the island of Djurgården so you don't stray too far out into the shipping lanes! Lots to see here... beuatiful parks as well as great architecture on Strandvägen and the villas on the southside of the island. Another option is to paddle in the lake called Brunnsviken on the northern outskirts of Stockholm. Haga Park surrounds the lake with lots of interesting things to see like Haga Castle and Stockholm University... you also don't have to worry about larger boats! The place to rent kayaks here is Brunnsvikens Kanotcentral.
Their websites, that I've linked, are in Swedish so it is better to contact me directly at the hotel for prices and directions on how to get there as well as other practical information. Have fun!
If you are feeling more adventurous then you can do a full day of kayaking out in the beautiful archipelago. Stockholm Adventures offers tours all summer, Thursdays through Sundays. The price is approximately 1,000 SEK (depends on the day) and includes lunch. You leave Stockholm at about 9am and head to the town of Stavsnäs where you will be met by the guide. You will be back in Stockholm at around 6pm.