Reserva Natural de Humacao (Carr. 3, km 74.3, Humacao, 787/852-6058, Mon.–Fri. 7:30 a.m.–3:30 p.m.; Sat.–Sun. and Mon. holidays 7:30 a.m.–6 p.m. May–Aug.; Sat.–Sun. and Mon. holidays 7:30 a.m.–5:30 p.m. Sept.–Apr., free) is a lovely natural reserve containing 3,186 acres of swamps, marshes, channels, and an interconnected lagoon system perfect for kayaking. There are also six miles of walking and bike trails. Sights along the way include an antique water-pumping station and bunkers constructed during World War II.
Tour outfitters Water Sports & Ecotours  operates out of the reserve, offering walking tours for $3.50 per person and kayak rentals for $10 per hour per person.