There are a total of 780 km of highways and roads in Dominica, 393 km of which are paved, leaving 387 unpaved, according to a 1996 estimate. There are no railways. Driving is on the left-hand side of the road. Some of the roads in more rural areas are rough and unpaved, and require a four-wheel drive vehicle. Dominica has three ports of entry: Portsmouth, Roseau, and Anse-de-Mai. Portsmouth and Anse-de-Mai are located in the northern region of the island, and Roseau is in the south. According to a 1999 estimate, there are no merchant marines. There are two airports, having paved runways of 914 and 1,523 meters.