Laguna de Aculeo is a shallow, sediment-dammed lagoon located near the town of Paine in Maipo Province, roughly one hour south of Santiago in the Metropolitan Region. At its historical peak the lagoon covered approximately 12 square kilometers with an average depth of around 6 meters, though it dried completely by 2018 following a prolonged drought combined with groundwater extraction and river diversion. Rainfall in subsequent years has partially refilled the lagoon, and it is currently in a state of ecological recovery, meaning water levels can vary considerably from year to year.

The lagoon's name derives from the Mapuche term Acum-Leu, meaning "where the river ends." It sits amid rolling hills and farmland, and its shallow, calm character makes it well suited to flatwater paddling. Guided kayaking tours operate on the lagoon, typically running around three hours on the water and limited to small groups of twelve participants. These tours focus on birdwatching, with species including black-necked swans, white herons, and marsh ravens present in the recovering wetland.

Access to the shoreline is largely privatized, which limits independent put-in options. Visitors should verify current access arrangements before planning an unguided trip. Spring and early summer are generally considered the most favorable seasons for a visit, with temperatures ranging from roughly 14°C to 30°C depending on the time of day and month.

Because the lagoon only partially refilled after the 2018 drought, water levels remain unpredictable on a year-to-year basis. Paddlers planning a trip should confirm that sufficient water exists before traveling, as conditions can change substantially between seasons. The lagoon's shallow depth and calm, enclosed character mean there is no significant whitewater or tidal influence, making it accessible to paddlers of modest skill levels when water is present.