On the Atlantic side it drains most of Venezuela's river waters. The largest basin in this area is the extensive Orinoco basin whose surface area, close to one million km2, is greater than that of the whole of Venezuela, although it has a presence of 65% in the country. The size of this basin - similar to that of the Danube - makes it the third largest in South America, and it gives rise to a flow of some 33,000 m³/s, making the Orinoco the third largest in the world, and also one of the most valuable from the point of view of renewable natural resources. The Rio or Brazo Casiquiare is unique in the world, as it is a natural derivation of the Orinoco that, after some 500 km in length, connects it to the Negro River, which in turn is a tributary of the Amazon. The Orinoco receives directly or indirectly rivers such as the Ventuari, the Caura, the Caroní, the Meta, the Arauca, the Apure and many others. Other Venezuelan rivers that empty into the Atlantic are the waters of the San Juan and Cuyuní basins. Finally, there is the Amazon River, which receives the Guainía, the Negro and others. Other basins are the Gulf of Paria and the Esequibo River.