Bahia Honda State Park occupies most of Bahia Honda Key, about 12 miles east of Big Pine Key, and is widely considered the best beach in the Florida Keys. Sandspur Beach on the Atlantic side has the postcard combination: white sand, turquoise water that stays shallow for a long way out, and the dramatic silhouette of the old Overseas Railroad bridge rising from the water just offshore. The water clarity is excellent, and snorkelling is possible directly from the beach.
The Bahia Honda Rail Bridge — the bridge section that remains — was part of Henry Flagler's Florida East Coast Railway, which reached Key West in 1912 after years of construction across open water. The 1935 Labor Day hurricane destroyed much of the railroad, and the roadbed was later converted into the Overseas Highway. The old railroad bridge at Bahia Honda couldn't be adapted for cars because its roadway was too narrow, so it was bypassed but left standing. It's now one of the most photographed structures in the Keys.
The park has three beaches, a marina, kayak rental, snorkel tours, and campground sites that book up months in advance during winter. Arrive early on weekends — the parking fills by mid-morning in season.