Osijek has two tram lines. Line 2 connects the train and bus station with Trg Ante Starčevića in the centre (but in a roundabout way, which takes you to the outer edge of town first), and line 1 goes to Tvrđa. The fare is 10KN, which you pay to the driver.
Buses connect Osijek to nearby Bilje; from the bus station take a Panturist bus heading to Beli Manastir or Batina and get off in Bilje (16KN, 20 minutes).
Taxi service Cammeo has modern cars and is very affordable; most rides in town cost just 20KN.
For bike trips to Kopački Rit Nature Park, try Šport za Sve.