Laguna de Sonso Nature Reserve, Nature reserve in Valle del Cauca Department, Colombia.

Laguna de Sonso is a 2,045-hectare reserve of marshes and lagoons on the east bank of the Cauca River, between Buga, Yotoco and Guacarí, at 935 m altitude. It holds the last extensive remnant of original natural wetland in the Cauca River Valley, and the introduced water hyacinth now covers parts of its waters.

Protection began in 1978 to preserve the last major natural wetland landscape in the Cauca Valley. Earlier environmental changes had significantly reduced such habitats throughout the region, making this area essential for conservation.

Local communities engage directly in conservation work and use the area for nature observation and environmental learning. Visitors encounter places where people actively participate in protecting the wetlands through sustainable practices.

The reserve lies on the east bank of the Cauca River between the municipalities of Buga, Yotoco and Guacarí, at an altitude of 935 m. Access is from Buga; the wetlands are reached from the Buga–Mediacanoa road. Water levels vary through the year, changing the look of the marshes and lagoons.

The horned screamer, a large bird with a bony spike on its head, survives here as the region's only remaining population. Birders also seek the grayish piculet, apical flycatcher, bar-crested antshrike and scrub tanager, species recorded in the reserve's marshes and lagoons.