Isla Apipé or Isla Apipé Grande is an about 25 km long Argentine

Argentina

Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...

 island in the Paraná River

Paraná River

The Paraná River is a river in south Central South America, running through Brazil, Paraguay and Argentina for some . It is second in length only to the Amazon River among South American rivers. The name Paraná is an abbreviation of the phrase "para rehe onáva", which comes from the Tupi language...

, on the border with Paraguay

Paraguay

Paraguay , officially the Republic of Paraguay , is a landlocked country in South America. It is bordered by Argentina to the south and southwest, Brazil to the east and northeast, and Bolivia to the northwest. Paraguay lies on both banks of the Paraguay River, which runs through the center of the...

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Isla Apipé is part of Corrientes Province

Corrientes Province

Corrientes is a province in northeast Argentina, in the Mesopotamia region. It is surrounded by : Paraguay, the province of Misiones, Brazil, Uruguay, and the provinces of Entre Rios, Santa Fe and Chaco.-History:...

, but the island is separated from the rest of the province by a channel of the Paraná River, which belongs to Paraguay. The island and some smaller islets are thus surrounded by Paraguayan waters, creating an enclave.