Why walk, take the bus, the tramway or the tunnelbana when you can take the boat to get around in Stockholm? There is Djurgårdsfärjan between Slussen (next to Gamla stan), Djurgården (next to Gröna lund) and Skeppsholmen. Depending on the season and the schedule, there are boats every 10 to 30 minutes between those three places. The nice part is that there is basically a free sightseeingtour included and you can stay outside to enjoy the view. When you start at Slussen, you see Gamla stan on the back of the boat, Skeppsholmen on the left, and the big cruiseships on the right. Before seeing Djurgården appear and hearing the screams of the people at Gröna Lund. On busy times - especially when Gröna Lund closes at 22h in the evening in summer or if there was a big event there or at Skansen - it can happen that you'll have to skip a boat. But for big events, they also increase the traffic, so waiting is never long. In the evenings and on some hours of the day, not all the boats of Djurgårdslinjen stop at Skeppsholmen and you have to push a button at the station if you're there and want a boat to stop. Sometimes it goes to Skeppsholmen on the way from Slussen to Djurgården, sometimes the other way round. If you want to go to Skeppsholmen, just tell someone from the staff.
Djurgårdsfärjan is definitely my favorite way of getting around in Stockholm. All you need is a valid SL-ticket or enough money for a single journey on your SL Access card. And the best: Djurgårdsfärjan is also included in your 24h/72h/7d-travelcards. Find the current schedule for line 82 on the SL-website and off you go!