Transport in Slovakia is possible by rail, road, air, or rivers. Slovakia is a developed Central European country with a well-developed rail network (3,662 km) and a highway system (854 km). The main international airport is the M. R. Štefánik Airport in the capital, Bratislava. The most important waterway is the river Danube, which is used by passenger, cargo, and freight ships. The two most important harbours in Slovakia are Komarno harbour and Bratislava harbour.[citation needed]