The northeast of Argentina is known as the Mesopotamia region because it is bordered by two great rivers, the Paraná and the Uruguay that separate this part of the country from its neighbors Paraguay, Brazil, and Uruguay. The region is geographically complex, containing tepid wetlands, wooded hills and mountains, and lush rainforests and waterfalls. Each of these environments is home to unique biodiversity unlike that seen throughout the rest of Argentina. Both Corrientes and Misiones Provinces are home to a large number of plants used for medicinal purposes, with at least 445 plants having been identified for local use.
A majority of Corrientes Province contains wetlands, rivers, lagoons, and underground water tables. The geography is fairly flat and open until reaching the hilly northern Campos district bordering Misiones Province. Most of the communities in the province are small and cattle ranches form one of the major economies of the region. While the province is small in human population, it has a large diversity of flora and fauna, especially of animals, including caiman, capybera, marsh deer, and birds living in undisturbed wetland areas. The 1.3 million hectare wetland area known as Esteros del Iberá was declared a Wetland of International Importance on January 18, 2002, as part of the RAMSAR Convention.
Misiones Province contains the only portion of the remaining Interior Atlantic Forest in Argentina. This rainforest, known as the Paraná Forest, contains the largest continuous block of forest (11,300 km2) that once occupied 1,000,000 km2 in the countries of Brazil, Paraguay, and Argentina. In 1999, the provincial government created a green corridor of 1,100,000 hectares to allow for the unhindered movement of wildlife, including jaguars, ocelots, and other large jungle cats. Additionally the province contains the habitat of at least 229 species of birds. This province is heavily promoted by the tourism sector because its biodiversity offers tourists views of exotic birds, animal species, and flora, often in the areas of spectacular waterfalls and waterways at the Iguazú National Park (recently voted as one of the new 7 Wonders of the World), the Urugua-í Provincial Park, the Yabotí Biosphere, and the Moconá Provincial Park.