The "costa" (coast), to the west, is a narrow plain, largely arid except for valleys created by seasonal rivers. The "sierra" (highlands) is the region of the Andes; it includes the "Altiplano" plateau as well as the highest peak of the country, the Huascarán. The third region is the "selva" (jungle), a wide expanse of flat terrain covered by the Amazon rainforest that extends east. Almost 60 percent of the country's area is located within this region. The country has fifty-four hydrographic basins, fifty-two of which are small coastal basins that discharge their waters into the Pacific Ocean. The other two are the Amazon basin, which empties into the Atlantic Ocean, and the endorheic basin of Lake Titicaca, both delimited by the Andes mountain range. In the second of these basins, the giant Amazon River begins, which, with its 6872 km, is the longest river in the world, with 75% of the Peruvian territory. Peru contains 4% of the planet's fresh water.