Railways extend 1,998 km (1,241 mi) across Lithuania, providing rail access to the Baltic Sea for Vilnius, Kaunas, and other major urban areas in 2002. About 44,000 km (27,341 mi) of the 35,500 km (22,059 mi) of highways are hard-surfaced. In 2002 there were 600 km (373 mi) of perennial navigable waterways. Sea routes link Klaipeda on the Baltic Sea with 200 foreign ports; Kaunas is the principal inland port. Also in 2002, the merchant fleet consisted of 47 ships (of 1,000 GRT or over) totaling 279,743 GRT, including 25 cargo vessels, 8 combination bulks, 2 oil tankers, 1 railcar carrier, 6 refrigerated cargo, 2 roll-on/roll-off cargo, and 3 short-sea passenger. A railway sea ferry from Klaipeda to Mukran (Germany) began in 1986. There are 72 airports, 9 with paved runways in 2001. Principal airports include Palanga, Vilnius, and Kaunas International at Kaunas, and one commercial airport in Siauliai. Two international airlines serve Lithuania: Lithuanian Airlines and Lietuva. In 2001, 304,100 passengers were carried on scheduled domestic and international airline flights.