Papua New Guinea is largely mountainous, and much of it is covered with tropical rainforest. The New Guinea Highlands run the length of New Guinea, and the highest areas receive snowfall—a rarity in the tropics. Within Papua New Guinea Mount Wilhelm is the highest peak, at . There are several major rivers, notably the Sepik River, which is long, which winds through lowland swamp plains to the north coast, and the Fly River at in length, which flows through one of the largest swamplands in the world to the south coast. The Highlands consist of a number of smaller ranges running west to east, such as the Finisterre Range which dominates the Huon Peninsula to the north of the city of Lae. At it is the world's third largest island country.