4-Day Overseas Highway Road Trip: Key Largo to Key West

There is only one road, and it runs out into the ocean.

The short version: the Overseas Highway is roughly 113 miles of US-1 from Florida City to Key West across 42 bridges, and four days is the right amount of time to drive it without rushing — one day each in the Upper, Middle, and Lower Keys plus Key West. You can do it in a long day, but you would skip Bahia Honda, the Key deer, and every reason the drive is worth doing. The best window is November through May. The real risk isn’t the driving; it’s the traffic on a two-lane road with no alternate route.

US-1 leaves the Florida mainland at Florida City, drops onto a thread of asphalt called the Overseas Highway, and then does something no other American highway does: it keeps going across open water, island to island, for 113 miles, all the way to a buoy in Key West that marks the southernmost point of the continental United States. Forty-two bridges. The longest, the Seven Mile Bridge, is exactly what it sounds like.

This is a sightseeing road trip, not a dive trip. You can snorkel along the way — and you should — but the point here is the drive: the bridges, the towns counting down by mile marker, the slow southward unspooling of the country until there’s no more country left.

The trip is rated moderate. The driving is easy. What makes it moderate is the logistics: the traffic that can turn a two-hour leg into four, the cost of everything, and the fact that there is no Plan B route if US-1 closes.

Keys addresses run by mile marker (MM), not street numbers. They count down from around MM 113 in Key Largo to MM 0 in Key West. Learn to read them — every business, beach, and turn here is “at MM 47.”

Overview

Four days, north to south, one night each in roughly the right place so you’re never doubling back. Key Largo and Islamorada (Upper Keys) on Day 1, Marathon and the Seven Mile Bridge (Middle Keys) on Day 2, Bahia Honda and Big Pine Key (Lower Keys) on Day 3, and Key West on Day 4.

The route: Florida City → Key Largo (MM 113–90) → Islamorada (MM 90–72) → Marathon (MM 53–47) → Seven Mile Bridge → Bahia Honda (MM 37) → Big Pine Key (MM 30) → Key West (MM 0). About 113 miles of Overseas Highway end to end.

Best time: Winter and spring (November through May). Driest weather, calmest water, clearest views from the bridges — and the highest prices and thickest crowds. Book lodging well ahead in this window. Avoid hurricane season (June–November) if you can.

Base camp logic: Sleep in Islamorada (Night 1), Marathon or Big Pine (Night 2), Key West (Nights 3 and 4 — or just Night 3 if you’re driving back out). Moving your hotel each night sounds like a hassle but saves hours of backtracking on a one-lane-each-way road.

Day by Day

Day 1 — Upper Keys: Key Largo and Islamorada

Leave the mainland early; the Florida City stretch of US-1 jams up by mid-morning on weekends. Your first real stop is John Pennekamp Coral Reef State Park (MM 102.5, Key Largo) — the first undersea park in the US. You don’t have to get on a boat. The visitor center, a small aquarium, and easy shore trails are enough for a road-trip pace, though the glass-bottom-boat and snorkel tours are the reason most people stop.

Nearby in Key Largo: the Florida Keys Wild Bird Center, a free rehabilitation sanctuary for pelicans, herons, and ospreys, and — for a particular kind of traveler — the actual African Queen, the steam launch from the 1951 Bogart film, which still runs canal cruises.

Drive south into Islamorada (“the Village of Islands”). The unmissable stop is Robbie’s of Islamorada (MM 77.5), where for the price of a bucket of baitfish you can hand-feed 100-pound tarpon that boil the water at the dock. It’s touristy and it’s wonderful. Add the History of Diving Museum if it’s raining, and Anne’s Beach (MM 73.5) — a shallow, mangrove-lined flat that’s more a wading spot than a sunbathing beach, but a genuine pretty pause.

Sleep: Islamorada.

Day 2 — Middle Keys: Marathon and the Seven Mile Bridge

The Middle Keys are the road trip’s natural-history day. In Marathon, Curry Hammock State Park (MM 56) protects one of the largest tropical hardwood hammocks in the Keys and is a famous fall hawk-migration site. The Turtle Hospital (MM 48.5) runs guided tours of a working sea-turtle rehab facility — book ahead, the slots fill. Crane Point Museum and Nature Center (MM 50.5) bundles a small natural-history museum with trails through hammock and mangrove.

Then the headline: the Seven Mile Bridge. The modern bridge carries US-1; running beside it is the old bridge, built on Henry Flagler’s railroad piers. A restored section leads to Pigeon Key, a tiny island that housed the railroad’s construction workers a century ago — you can walk or take a shuttle out for the view back along both bridges. It’s the best photograph on the whole highway.

A note on the bones underneath: Flagler’s Overseas Railroad reached Key West in 1912, an engineering folly that actually worked — until the 1935 Labor Day Hurricane, one of the strongest ever to hit the US, destroyed it and killed hundreds. The state bought the wreckage and rebuilt it as a highway. You are driving on a ghost.

Sleep: Marathon or Big Pine Key.

Day 3 — Lower Keys: Bahia Honda and the Key Deer

Just past the Seven Mile Bridge, Bahia Honda State Park (MM 37) is, honestly, one of the best beaches in Florida — which in the Keys is a higher bar than it sounds, because most “beaches” here are thin and rocky. Bahia Honda has real sand, swimmable water, and a dramatic photo op: the broken span of the old Bahia Honda railroad bridge arcing off into the channel. Go early; the parking lot caps out and closes by late morning on busy days. If this is the stop you most want to get right, our full guide to Bahia Honda State Park covers the beaches, the snorkel concession, and the camping reservations in detail.

A few miles down, Big Pine Key (MM 30) is home to the National Key Deer Refuge and its star residents — Key deer, an endangered subspecies the size of a large dog, found nowhere else on Earth. They wander the residential streets at dawn and dusk. Drive slowly: the night speed limit drops to 35 mph specifically to keep from hitting them, and cars are their leading cause of death. The No Name Pub, a famously hard-to-find dive bar wallpapered in dollar bills, is the local lunch institution.

Offshore here is Looe Key, a superb reef for snorkelers if you want to add a half-day on the water; it needs a boat. If you find yourself wanting more reef time than this driving trip allows, our 3-day Florida Keys snorkel itinerary is built around exactly that. Otherwise, push on to Key West for the night.

Sleep: Key West.

Day 4 — Key West: MM 0

You’ve arrived at the end of the road. Key West is small enough to do on foot and bike. The ritual is the Mallory Square sunset celebration — buskers, food carts, and a crowd applauding the sun as it drops into the Gulf. Get there 45 minutes early in season.

By day: the Southernmost Point buoy (expect a line for the photo — it’s a painted concrete marker, manage expectations), the bars and shops of Duval Street, and the Ernest Hemingway Home and Museum, where roughly 60 cats — many of them six-toed, descendants of Hemingway’s own — own the grounds. For the actual beach, skip the crowded ones and go to Fort Zachary Taylor State Park: the best swimming, the best snorkeling, and a Civil War-era fort, all in one.

If you have a spare day and real ambition, the Dry Tortugas — Fort Jefferson and pristine reef, 70 miles further out — are reachable only by ferry or seaplane and deserve a full day of their own. Don’t try to cram it into the afternoon.

What to Pack

• Sun protection — The Keys sit at 24°N; the UV is brutal even in winter. Reef-safe sunscreen (zinc or titanium, no oxybenzone), a hat, and sunglasses.
• Reusable water bottles — Everything is pricier down here, including a bottle of water at MM 50.
• A real road map or offline maps — Cell coverage drops in stretches along US-1. You only need one road, but you’ll want mile-marker awareness offline.
• Bug spray — Mosquitoes and no-see-ums are serious in the mangrove zones, especially at Bahia Honda and Big Pine at dawn/dusk.
• Swimsuit and a quick-dry towel — For Bahia Honda and Fort Zach.
• Patience for traffic — Pack snacks. You’ll sit in some.
• Cash — For the No Name Pub, Robbie’s bait buckets, and the odd cash-only shack.

Getting There

From Miami International Airport, it’s about 60 miles to Key Largo (roughly 1.5 hours without traffic) and another 100 miles to Key West. Take the Florida Turnpike south to its end at Florida City, then US-1 onto the Overseas Highway. There is no other route into the Keys — this is the only road.

Logistics worth knowing:

• Fill the gas tank in Florida City before you start south. Keys gas runs 20–40 cents a gallon higher.
• Mile markers are your address system. Tell your hotel “I’m at MM 47” and they’ll know exactly where you are.
• Rent the car in Miami, not Key West — one-way Keys drop-offs are expensive, and you’ll want the car for the whole trip anyway.
• Tolls: the Turnpike is tolled (have a transponder or a rental with one); the Overseas Highway itself is free.

Honest Caveats

• The traffic is the real risk. US-1 through the Keys is mostly two lanes with no alternate route. One fender-bender, one breakdown, one slow RV with nowhere to pass, and everyone behind it is stuck — sometimes for an hour or more. Never book a tight ferry or flight connection on the same day as a long drive. Drive the long legs early.
• It is expensive. Keys lodging is some of the priciest in Florida, and it books out months ahead in winter and spring. Food, gas, parking, and tours all run above mainland prices. Budget accordingly, or come in the shoulder season (May or November) and accept slightly worse odds on weather.
• Hurricane season is genuine. June through November carries real risk, and the Keys have exactly one evacuation road. Watch the forecast; have a flexible cancellation policy on bookings.
• The “beaches” are modest. The Keys are coral and mangrove, not sand. Limited natural beach, frequent sargassum seaweed wrack lines, and shallow rocky entry are the norm. Bahia Honda and Fort Zachary Taylor are the real exceptions — plan your beach time around those two and you won’t be disappointed.
• It can feel touristy. Long stretches of US-1 are strip malls, bait shops, and chain motels. The magic is at specific stops you have to seek out — not on the highway itself.

Plan Your Visit

• Best season: November through May for the driest weather, calmest water, and clearest bridge views. Hurricane season runs June through November.
• Drive time: About 113 miles end to end. Non-stop is 2.5 to 3 hours; budget a half-day per leg if you actually stop.
• State park fees and hours: The Florida state parks along the route are open 8 a.m. to sundown, 365 days a year. Entry runs roughly $4.50 to $8 per vehicle plus a 50-cent-per-person Monroe County surcharge. As of 2026, Bahia Honda is $8 per vehicle (2–8 people) and Fort Zachary Taylor is $6 per vehicle (its fort closes at 5 p.m.). No reservation is needed to enter, but Bahia Honda’s parking lot fills and closes by late morning on busy days, so arrive early.
• Access: US-1 is the only road in and out. There is no alternate route — a single closure strands the whole chain.
• Drive safe at Big Pine Key: The night speed limit drops to 35 mph through the National Key Deer Refuge specifically to protect the endangered Key deer. Slow down at dawn and dusk.
• What to bring: Reef-safe sunscreen, a hat, sunglasses, bug spray, a swimsuit and quick-dry towel, refillable water bottles, offline maps for the coverage gaps, and cash for the cash-only stops.

Frequently Asked Questions

How long does it take to drive the Overseas Highway?

Non-stop, Key Largo to Key West is about 100 miles and takes roughly 2.5 to 3 hours — if nothing goes wrong. But nothing driving US-1 is non-stop. It is mostly a two-lane road with no alternate route, so a single accident or a slow RV strands everyone behind it for an hour. Plan the full 113-mile run from Florida City as a half-day if you stop, and never schedule a tight ferry or flight connection at the Key West end.

What is the best time of year to drive the Keys?

November through May. Winter and spring bring the driest weather, calmest water, and the best visibility — but also peak crowds and peak lodging prices, which book out months ahead. Hurricane season runs June through November and is a genuine risk in the Keys, where there is exactly one road out. Summer is hot, humid, buggy, and stormy by afternoon, though hotel rates ease.

Do I need to stop at every mile marker town?

No. The Keys reward picking a few stops and doing them properly over racing through all of them. This four-day plan spends roughly one day each in the Upper Keys, Middle Keys, Lower Keys, and Key West. If you only have two days, do Key Largo or Islamorada on day one and drive straight to Key West on day two — but you will miss Bahia Honda and the Key deer, which are the quiet highlights.

Do I need to pay to enter the state parks?

Yes, the state parks charge a small per-vehicle entrance fee — roughly $4.50 to $8 depending on the park, plus a 50-cent-per-person Monroe County surcharge. As of 2026, Bahia Honda is $8 per vehicle and Fort Zachary Taylor is $6. No advance reservation is needed just to get in, but popular lots like Bahia Honda’s fill early on busy days.

Is four days enough, or should I take longer?

Four days is the comfortable sweet spot: one day each in the Upper, Middle, and Lower Keys plus Key West, with no backtracking. Add a fifth day if you want the Dry Tortugas, which need a full day of their own by ferry or seaplane. Two days is the bare minimum and forces you to skip Bahia Honda and the Key deer.