Modes of transport in the Central African Republic include road, water, and air. Most but not all of the country is connected to the road network, much of which is unpaved, and which centres on the routes nationales identified as RN1 to RN11. Bangui serves as a seaport, and 900 km of inland waterways are navigable, the main route being the Oubangui river. There is one international airport at Bangui-Mpoko, two other paved airports, and over 40 with unpaved runways.