With nearly 40 miles of riparian vegetation, this 56,000-acre area is teeming with plant and animal life. Highly popular with bird watchers (more than half of the known breeding bird species in the U.S. have been spotted here); visitors can hike solo or choose from regularly scheduled bird, interpretive, and river walks led by docents from the San Pedro House. 9:30 a.m. to 4:30 p.m. daily. Hikers, mountain bikers, equestrians, and dogs are welcome. 800-288-3861 or 520-508-4445 (San Pedro House).