Lago Peñuelas National Reserve, National reserve in Valparaíso Province, Chile.

Lago Peñuelas National Reserve is a protected area in Valparaíso Province featuring Mediterranean forests, wetlands, and an artificial lake surrounded by native vegetation. The reserve covers roughly 9,260 hectares and supports a wide variety of plant and animal life throughout its landscape.

The reserve was established in 1952 following construction of Peñuelas Lake between 1895 and 1900 to supply water to Valparaíso and Viña del Mar. This water project eventually became the basis for protecting the surrounding land as a nature reserve.

The reserve forms, with La Campana National Park to its north, the Campana-Peñuelas Biosphere Reserve, designated by UNESCO in 1984. Researchers have used the unit to study its flora, recording about 150 native species; 14 of 300 assessed are in conservation trouble, two of them endangered.

The reserve is accessible via Route 68 connecting Santiago and Valparaíso, and facilities are open on weekends and holidays from 8:45 to 19:00. Visitors should bring sturdy shoes for walking and check opening hours before planning a visit.

The area is home to around 150 native plant species and approximately 120 bird species, including endangered plants and mammals such as the Leopardus colocolo. This concentration of rare species makes it particularly important for conservation in the region.