Santa Marta's centre is compact and walkable. For longer trips, taxis are the quickest option but not always the cheapest -- agree on the fare before getting in, and ask your hotel for typical prices to common destinations. Drivers are required by law to show you the list of official fares if you ask.
Local buses run set routes around the city and to nearby areas like Taganga and El Rodadero for about 1,000 pesos. Private "door-to-door" shuttle services offer a more comfortable alternative, picking you up and dropping you off at your chosen address for a modest premium over the bus fare.