Bahia Honda (deep bay, in Spanish) is part of the Florida Keys. Situated 12 miles (19 km) south of Marathon, at the west end of the Seven Mile Bridge (mile marker 37), the virtually unhabited 524 acre (2.1 km²) island is the home of the Bahia Honda State Park, founded in 1961. Several rare plants, including yellow satinwood, silver and key thatch palms, and the endangered small-flowered lily thorn, are found in the park. The 2.5 mile (4 km) natural, white sand beach was at one time named the best in the continental U.S.

The channel at the island's west end is one of the deepest natural channels in the Florida keys. Part of the old Bahia Honda Bridge is accessible from the park.