Southwest of the city of Orotina, as the crow files, in the lower river basin of the River Grande de Tárcoles, which waters the Central Occidental or Western Valley.  It ranges from the rolling alluvial lowlands to the steep slopes of volcanic and sedimentary hills that rise 634 meters above sea level.

Despite the fact that the reserve is small, remote and frequently visited by poachers, it houses a very diverse wildlife. Over 100 pairs of scarlet macaws, perhaps the most beautiful birds of the pacific side of Costa Rica, live and nest in the forests. The reserve also provides shelter for howler and white-faced capuchin monkeys, white-tailed deer, red brocket deer, collared peccaries, pacas, rattlesnakes and fer-de-lance snakes. The swamps, an area where the river overflows, are where cayenne wood-rails, raccoons, lizards and several species of snakes and frogs find food and shelter. Crocodiles, which can grow 3 metres long and are an endangered species, lie on the shore here and also on the beaches along the River Grande de Tárcoles.

The dry season, from December to May, is the best time to visit the reserve.  The rainy season lasts from May to November, with the heaviest rainfall in September and October.  Average annual rainfall varies between 2,400-3,100 mm., which is a large amount and one of great importance to preserve the evergreen forest.  The climate is hot and very humid, with average annual temperatures between 24º C and 27º C.