The Amazon River in South America is the largest river by discharge volume of water in the world, and by some definitions it is the longest. Its width varies according to the rain season; at its widest point it can be 6.8 miles or 11km during the dry season and 24.8 miles or 40km during the rainy season. Where the river meets the Atlantic Ocean its width reaches 150 miles or 240 km. The river is so wide that in some parts it is impossible to see from one bank to the opposite; people sometimes refer to the Amazon River as the "river sea".
The Amazon River flows east from the Peruvian Andes across Brazil and empties into the Atlantic Ocean. In 2000, a National Geographic Society expedition found that its most distant source is the melting snow cap of a mountain called Nevado Mismi in the Peruvian Andes. The stream of melting snow forms the Apurimac River which later joins the Ucayali River in east central Peru. The Ucayali River meets the Marañon River near the city of Iquitos, Peru forming the mighty Amazon River.