What are the best day trips from Key West?

The Yankee Freedom III departs the Historic Seaport at 8am and returns by 5:15pm. The crossing takes about 2 hours and 15 minutes each way. Round-trip tickets run $220 per person as of 2026, breakfast and lunch included. Fort Jefferson sits on Garden Key. Construction started in 1846, and the hexagonal brick fortress remains the largest masonry structure in the Americas. You get about 4.5 hours on the island. The ferry provides snorkeling gear, and the moat wall drop-off has 40 to 60 feet of visibility on calm days. Water temperature hovers near 84°F in September. A full ferry carries maybe 300 people, but most scatter across the fort's three tiers. You'll find quiet corners on the second level where the salt wind comes through the gun ports. Pack SPF 50 reef-safe sunscreen and water shoes for the coral. The crossing gets rough in September swells, so take Dramamine 30 minutes before boarding if either of you is prone to seasickness.

Bahia Honda State Park sits at Mile Marker 37, about 45 minutes north on US-1. Entry is $8 per vehicle plus $0.50 per person. Sandspur Beach on the Atlantic side has pale, soft sand, nothing like the coral rubble at most Lower Keys shorelines. The old Bahia Honda Rail Bridge, part of Henry Flagler's railroad completed in 1912, frames the south end of the park. On the drive back, stop at the National Key Deer Refuge on Big Pine Key, 7 miles south. The miniature Key deer stand about 28 inches at the shoulder and tend to browse near Watson Boulevard around dusk. One of you can swim at Sandspur while the other reads under the Australian pines, and the 5-hour loop gets you back to Key West for a 7pm dinner reservation.

Marathon sits at Mile Marker 50, roughly an hour north. The Turtle Hospital at 2396 Overseas Highway runs 90-minute guided tours for $30 per person. Book ahead, they cap groups at 25. The rescue facility holds around 60 sea turtles at any given time, and the outdoor tanks let you get close enough to smell the salt and algae on the shells. If one of you wants to fish while the other prefers galleries and lunch, push another 30 miles to Islamorada. The Hungry Tarpon at Robbie's Marina serves solid fish tacos for $14, and you can hand-feed tarpon off the dock for $5 in bait fish. The tarpon run 80 to 100 pounds and splash hard enough to soak your shirt. Half-day backcountry charters run $500 to $600 for two out of Bud N' Mary's Marina. The non-fishing partner can rent a kayak at Anne's Beach, 5 miles south. Meet back at the marina by 3pm and drive south together.

Skip the Everglades as a day trip from Key West. The Flamingo Visitor Center is 160 miles north through Homestead, and 3.5 hours of driving each way eats most of your light. Miami is worse at 165 miles, with return traffic on US-1 adding an hour. If you want mangrove channels without the drive, Lazy Dog Adventures on Stock Island runs 2-hour kayak tours for $60 per person. September is hurricane season, so check NOAA marine forecasts the morning of any water trip. The Dry Tortugas ferry cancels in seas above 5 feet, and they'll call by 6am if it's scrubbed. Worth noting if you're driving the Keys as a couple. Much of US-1 above the Seven Mile Bridge is flat water, low mangroves, and concrete bridges. Load a 90-minute playlist for the car.