Reserva Ecológica Costanera Sur is a 350-hectare nature reserve on the banks of the Río de la Plata, the largest and most biodiverse green space in Buenos Aires despite sitting just minutes from the skyscrapers of Puerto Madero. Winding trails loop around three lagoons and lead to riverside overlooks, passing through meadows of pampas grass, alder forests, and stands of the cockspur coral tree, Argentina’s national flower.
More than 2,000 species of flora and fauna live in the reserve, including lizards, turtles, coypus, and roughly 340 recorded bird species — it’s common to spot 50 different birds during a single two-hour walk. Free guided tours describing the reserve’s wildlife and history run on weekends and public holidays at 10:30 a.m. and 3:30 p.m.
The reserve is open Tuesday through Sunday, with hours running 8 a.m. to 6 p.m. from April to October and 8 a.m. to 7 p.m. from November to March; admission is free. It’s a favorite local spot for walking, running, cycling, and picnics, so weekends can get busy despite the size of the grounds.