Lagoon Mirim

Lagoon Mirim (Laguna Merín / Lagoa Mirim) is a large coastal lagoon that lies along the border between Uruguay and Brazil, occupying a shallow basin of coastal flatlands. The lagoon is an important regional wetland and supports fisheries, seasonal birdlife and traditional local uses.

The lagoon’s waters and connected channels influence agricultural and fishing communities on both sides of the border and the area includes marshes and riparian vegetation. Tidal influence is limited compared with open coastal estuaries, and water exchange with the ocean is indirect via connecting channels.

The lagoon area has been used for local fishing and small-scale navigation for centuries; modern management involves binational considerations for water use and habitat conservation. Wetland and bird populations make it a notable ecological feature in the region.

Lagoon Mirim sits along the Brazil-Uruguay border in eastern Uruguay (Cerro Largo Department) and adjacent areas of southern Brazil, within a low-lying coastal plain.

• Transboundary lagoon: A large transboundary coastal lagoon forming part of the border area between Uruguay and Brazil, important for local fisheries and wetland habitats.

• Visit early morning for the best birdwatching and calmer waters-many waterbirds are most active at dawn and visibility for wildlife watching is highest then.
• Remember Laguna Mirim/Lagoa Mirim is a transboundary lagoon shared with Brazil; if you plan to cross the water or visit settlements on the other side, carry ID and check local border rules in advance.
• Arrange a local guide or contact fishing communities in Cerro Largo for boat access and up-to-date local information-the lagoon is remote and guides know the safe launch points and productive areas.
• After heavy rain rural access roads can become difficult; check local road conditions or time your visit outside the wettest months to avoid getting stranded on unpaved tracks.