This 84,824-acre refuge was established in 1957 to protect the dwindling population of the Key deer, one of more than 22 animals and plants federally classified as endangered or threatened, including five that are found nowhere else on Earth. The Key deer, which stands about 30 inches at the shoulders and is a subspecies of the Virginia white-tailed deer, once roamed throughout the Lower and Middle Keys, but hunting, destruction of their habitat, and a growing human population caused their numbers to decline to 27 by 1957. The deer have made a comeback, increasing their numbers to approximately 750. The best place to see Key deer in the refuge is at the end of Key Deer Boulevard and on No Name Key, a sparsely populated island just east of Big Pine Key. Mornings and evenings are the best time to spot them. Deer may turn up along the road at any time of day, so drive slowly. They wander into nearby yards to nibble tender grass and bougainvillea blossom, but locals do not appreciate tourists
driving into their neighborhoods after them. Feeding them is against the law and puts them in danger.
A quarry left over from railroad days, the Blue Hole is the largest body of freshwater in the Keys. From the observation platform and nearby walking trail, you might see the resident alligator, turtles, and other wildlife. There are two well-marked trails, recently revamped: the Jack Watson Nature Trail (0.6 mile), named after an environmentalist and the refuge's first warden; and the Fred Mannillo Nature Trail (0.2 mile), one of the most wheelchair-accessible places to see an unspoiled pine-rockland forest and wetlands. The visitor center has exhibits on Keys biology and ecology. The refuge also provides information on the Key West National Wildlife Refuge and the Great White Heron National Wildlife Refuge. Accessible only by water, both are popular with kayak outfitters.