The Laguna Garzón sits on the boundary between Rocha and Maldonado, separated from the Atlantic by a sandbar that opens and closes with the seasons, and crossed by the circular bridge that made it famous. It is brackish, shallow, full of birds, and best seen from the water.
This outfit runs kayaking and guided nature trips on the lagoon, with a stated interest in the conservation side — "conocer, valorar, conservar" is the line on their own site, and the guiding is pitched accordingly rather than as a paddle-and-photograph.
Ruta 10 at km 193, where the bridge is. Their registration lists the village of Garzón inland, but the operation runs from the lagoon itself, which is where the pin sits. Book by WhatsApp.