Lagoon Mirim
General data
- Name: Lagoon Mirim
- Water system: Lagoa dos Patos
- Water type: Estuary
- Progression: Sao Goncalo Channel -> Lagoa dos Patos -> Rio Grande Channel -> Atlantic Ocean -> Planet Earth
- Climates: Tropical
- Continents: South America
- Countries: Brazil, Uruguay
Lagoon Mirim (Portuguese, pronounced [miˈɾĩ]) or Merín (Spanish, pronounced [meˈɾin]) is a large estuarine lagoon which extends from southern Rio Grande do Sul state in Brazil into eastern Uruguay. Lagoa Mirim is separated from the Atlantic Ocean by a sandy, partially barren isthmus. The Jaguarão/Yaguarón, Tacuarí and Cebollatí Rivers empty into Lagoon Mirim, while the São Gonçalo Channel connects it with Lagoa dos Patos to the north.