We are big fans of Stockholm's public transportion system. We overview the system's prongs here (metro, bus) and also give you the skinny on taxis and ferries. Most helpful of all, we tell you why you must buy a transportation pass.
Getting Around Stockholm

Metro
Don't be fooled by the fact that Stockholm only has three metro lines. Most of Stockholm's many attractions are located close to the city center, first off. Secondly, each metro line bifurcates into different prongs. So the range of territory covered by the metro is more extensive than you might assume.
A standard one-trip ticket costs 20 SEK. A prepaid strip of 16 tickets costs 180 SEK. If you plan on using the metro or bus more than once or twice, buying a prepaid strip of tickets or a day pass is the best option.
For more information about traveling with the Stockholm metro, see our blog poston Stockholm public transportation.
Buses
The Stockholm bus network fills in the metro's blanks. It canvasses the central city well, and coordinates with the metro system to boot. Note that tickets must be purchased before boarding the bus. A ticket or day pass is valid for either the bus or metro.
The Stockholm Card
The Stockholm Card covers transportation with the metro, bus, and more in addition to offering free admission to over 70 museums. It ranges from 375 SEK for 24 hours to 595 SEK for 72 hours.
Taxis
Taxis in Stockholm are very expensive. One of Stockholm's best-known taxi outfits, Taxi Stockholm, begins running the meter at SEK 45. Another, Taxi 020, imposes a starting cost of SEK 39. In both cases, fares rise steeply from there. We can't in good Cheapo conscience recommend that you ever take a taxi in Stockholm.
Ferries
Ferries through the archipelago are a great way to see the city and the region. Some ferry companies include Cinderella Båtarna and Strömma Kanalbolaget, which departs from conveniently-located Stadshusbron.
Also check out the Båtluffarkortet, or ferry pass. A 5-day ferry pass allowing unlimited boat travel through Stockholm's archipelago costs SEK 300. Check out the official Stockholm tourist site's ferry pass information.