Stockholm has an excellent public transportation system. One company, called SL (Storstockholms Lokaltrafik), runs all buses, subways, trams and commuter trains. Some boats can be travelled on using certain SL tickets... more about that later. This means that travelling through Stockholm is quite easy.
- The subway is very easy to understand, especially compared to the systems in larger cities like Paris, London & New York. There are three lines (blue, red and green) that cross the city like a starfish, all meeting under the Central Train Station.
- Buses travel all over the city and can take you quite far out into the countryside... there are 4 cross-town buses (1, 2, 3 & 4) which are easy to spot as they are blue instead of red.
- There is also a commuter train network (called "pendeltåg") if you are planning to travel to the outskirts of Stockholm or to get to the International Fair at Älvsjö. There are several trams and street car lines included in SL tickets. The ones that are important (from a tourist standpoint) is the line running out to Saltsjöbaden, a popular seaside resort, and the one connecting the Ropsten subway station to the island of Lidingö... where you can find the seaside town of Gåshaga as well as the sculpture garden at Millesgården. Finally you have an old fashioned street car travelling between the island of Djurgården and the NK department store.
- SL tickets/cards work on the two ferries going out to the island of Djurgården as well... though not one-time tickets.
The Stockholm Card works on all public transportation run by SL. They can be purchased at a tourist information center or a SL Center. Some hotels do sell them as well.