The drive to Marathon through the Florida Keys is one of the most scenic road trips in America. The Overseas Highway (U.S. Route 1) stretches across 42 bridges connecting a chain of tropical islands, with turquoise water, mangrove shorelines, and open ocean views the entire way. It’s the kind of drive where passengers press their faces against the window and drivers wish they could do the same.
But it’s also a drive with a few quirks that catch first-time visitors off guard — especially the speed limits. The Overseas Highway is aggressively patrolled, speed limits change frequently, and a ticket on the way to paradise is no way to start a vacation.
This guide covers everything you need to know: how long the drive takes, where to watch for speed traps, the best stops along the way, and tips for arriving at Blackfin Resort & Marina relaxed and ready for your Florida Keys adventure.
The Drive at a Glance
- From Miami: About 113 miles, 2.5–3 hours without stops (longer with traffic)
- From Fort Lauderdale: About 150 miles, 3–3.5 hours
- From Key West: About 50 miles, 1 hour
- Road: S. Route 1 (Overseas Highway) — the only road in and out of the Keys
- Blackfin Resort address: 4650 Overseas Hwy, Marathon, FL 33050 (Mile Marker 49.5)
- Tip: Take the Florida Turnpike south from Miami — do NOT take U.S. 1 through Homestead and Florida City. The Turnpike drops you directly onto U.S. 1 at Florida City with far less traffic
Understanding Mile Markers
Everything in the Florida Keys is measured by Mile Markers (MM) — small green signs on the side of the Overseas Highway. They start at MM 107 in Key Largo and count down to MM 0 in Key West. Addresses, directions, and locals all reference mile markers instead of street addresses. When someone tells you a restaurant is “at MM 54,” that’s your cue to watch the green signs.
Key landmarks by mile marker:
- MM 107: Key Largo — the first major island and start of the Keys
- MM 90–80: Islamorada — sport fishing capital, Robbie’s Tarpon feeding
- MM 65–47: Marathon — your destination! Blackfin Resort is at MM 49.5
- MM 47: Seven Mile Bridge — the iconic stretch connecting Marathon to the Lower Keys
- MM 33–29: Big Pine Key — Key deer habitat, reduced speed zone
- MM 0: Key West
Speed Limits & Speed Traps: What Every Driver Needs to Know
This is the section that could save your vacation — or at least save you a few hundred dollars. The Overseas Highway is one of the most heavily patrolled roads in Florida, and the speed limits change constantly. If there’s one thing experienced Keys travelers all agree on, it’s this: do not speed on the Overseas Highway.
How Speed Limits Work in the Keys
Speed limits on the Overseas Highway range from 35 mph to 55 mph, and they shift up and down frequently as you pass through populated areas, bridges, and stretches of open highway. The maximum is 55 mph on the bridges and open stretches between islands. It drops to 45 mph as you approach each island community, and then down to 35 mph in the more built-up areas. Some zones even have minimum speed limits (around 40 mph) to keep traffic flowing on the bridges.
The changes happen fast and the signs aren’t always big. If you’re chatting with passengers, changing the music, or admiring the view (understandable), it’s easy to miss one. That’s exactly what the patrol officers are counting on.
Who’s Patrolling
Two agencies work the Overseas Highway:
- Monroe County Sheriff’s Office — White cars with green stripes. Very active with radar throughout the Keys
- Florida Highway Patrol (FHP) — Black cars with tan roofs. Also regularly set up with radar on the highway
Both agencies actively run radar, and you’ll see them parked in medians, on bridge approaches, and in the transition zones where the speed limit drops. There’s no such thing as “making up time” on the Overseas Highway. Stick to the posted limit and enjoy the drive.
Where to Watch for Speed Traps
While enforcement happens everywhere, here are the areas where drivers most commonly get caught:
- Layton (around MM 68): This tiny community between Islamorada and Marathon is notorious among Keys drivers. The speed limit drops as you pass through, and there’s often a patrol car waiting. Even a parked decoy car has been known to make drivers hit their brakes
- Marathon transition zones (MM 60–50): As you enter Marathon, the speed drops from 55 to 45 to 35 through several quick transitions. This stretch catches a lot of first-time drivers who don’t slow down quickly enough
- Seven Mile Bridge approaches (MM 47): Both ends of the Seven Mile Bridge are popular enforcement spots. Drivers who’ve been cruising at 55 mph on the bridge sometimes don’t slow down fast enough as they reach the island
- Big Pine Key (MM 33–29): This is a Key Deer Wildlife Refuge zone with a special 45 mph daytime / 35 mph nighttime speed limit. The deer are small, endangered, and wander onto the road — especially at night. Police and wildlife officers enforce these limits strictly. If you’re driving to or from Key West through here after dark, go slowly
- Upper Keys (MM 107–90): The stretch between Key Largo and Islamorada sees active enforcement, particularly on weekends when traffic is heavier
- Night driving: Some sections have lower nighttime speed limits that are posted but easy to miss in the dark. Big Pine Key is the most critical, but pay attention to signs throughout the drive if you’re traveling after sunset
The bottom line: Set your cruise control to the posted limit, keep your eyes on the speed limit signs, and relax. The drive is beautiful, there’s no reason to rush, and a speeding ticket in Monroe County is expensive enough to ruin a vacation budget.
[Image: Speed limit sign on the Overseas Highway. Alt text: “Speed limit sign along the Overseas Highway in the Florida Keys”]
What the Road Is Actually Like
The Overseas Highway is well-maintained but has some characteristics that surprise first-time drivers:
- Two lanes in many sections. Large portions of the highway are just one lane in each direction. Passing is allowed only in marked zones. If you get stuck behind a slow vehicle, be patient — a passing lane will eventually appear
- U-turns are normal. There aren’t many traffic lights or large intersections in the Keys. You’ll frequently need to make U-turns to reach businesses and restaurants on the opposite side of the highway. Don’t be intimidated — it’s how everyone drives here
- Horizontal traffic lights. The few traffic lights in the Keys are mounted horizontally rather than vertically. It’s a small thing, but it throws people off the first time
- The 18-mile stretch. Between Florida City and Key Largo, the highway crosses an 18-mile stretch of mostly mangrove-lined road. This section can feel monotonous, but once you reach Key Largo the scenery opens up dramatically
- You’ll cross 42 bridges, including the iconic Seven Mile Bridge. Most bridges are two lanes each direction and have a 55 mph limit. Wind can be strong on the longer bridges — keep a steady grip on the wheel
- No rest areas. There are no official highway rest stops in the Keys. Use gas stations, restaurants, or state parks along the way when you need a break
Best Stops on the Drive to Marathon
The drive from Miami to Marathon is only 2.5 hours straight through, but it’s so much better when you slow down and make a few stops. Here are the highlights along the way:
Key Largo (MM 107–95)
Your first real taste of the Keys. John Pennekamp Coral Reef State Park is the first undersea park in the U.S., offering glass-bottom boat tours, snorkeling, and kayaking. It’s a great first stop if you want to stretch your legs after the 18-mile stretch from the mainland. There are also plenty of gas stations and restaurants here for fueling up.
Islamorada (MM 90–80)
Known as the Sport Fishing Capital of the World, Islamorada is the perfect lunch stop. Robbie’s Marina at MM 77.5 is a classic Keys experience — buy a bucket of bait and hand-feed enormous tarpon from the dock. The kids (and adults) will love it. Islamorada also has a growing restaurant scene and the iconic Rain Barrelartisan village with its giant lobster sculpture out front (great photo op).
Long Key State Park (MM 67)
A peaceful stop for a short nature walk or a wade in the shallow flats. The park features a boardwalk trail through tropical hardwood hammock and access to calm wading areas. It’s especially nice if you want a quiet break before the last stretch into Marathon.
Curry Hammock State Park (MM 56)
Just north of Marathon, this 1,000-acre state park has a beautiful beach, kayak rentals, and nature trails. It’s an ideal final stop before reaching Blackfin Resort, especially if the kids need to burn off some energy after the drive.
When to Drive: Traffic Tips
The Overseas Highway is the only road in and out of the Keys. There are no alternate routes. That means traffic bottlenecks are real, especially in certain situations:
- Friday afternoons: The worst time to drive south into the Keys. Weekend visitors from Miami and South Florida clog the Upper Keys from about 2 PM onward. If you can arrive before noon on Friday or wait until Saturday morning, you’ll have a much smoother drive
- Sunday afternoons: The reverse problem — northbound traffic heading back to Miami can be very heavy. If you’re leaving Marathon on Sunday, consider departing early morning or waiting until evening
- Holiday weekends: Memorial Day, Fourth of July, and Labor Day weekends bring the heaviest traffic of the year. Plan accordingly and add at least an hour to your estimated drive time
- Accidents: Because the highway is mostly two lanes with no alternate routes, a single accident can shut down traffic for hours. Download the Monroe County Sheriff’s Office app for live traffic updates and incident alerts
- Best times to drive: Weekday mornings or mid-afternoon tend to be the smoothest. Tuesday through Thursday are generally the lightest traffic days
Flying to Marathon
If you’d rather skip the drive, you have a few airport options:
- Marathon Airport (MTH): Marathon has a small airport that primarily serves private planes and charters. If you have access to a private aircraft, you can fly directly in — the airport is just minutes from Blackfin Resort
- Key West International Airport (EYW): About 50 miles south of Marathon (1 hour drive). Serves several major airlines with flights from major cities. Rent a car and drive north to Marathon
- Miami International Airport (MIA): The largest nearby hub, about 113 miles north (2.5–3 hour drive). The widest selection of flights and often the best fares. Rent a car and enjoy the scenic drive south
- Fort Lauderdale–Hollywood International Airport (FLL): About 150 miles north (3–3.5 hours). Often has the cheapest flights and budget airline options
What to Pack in the Car
- Sunglasses: The sun reflecting off the water on both sides of the highway can be blinding, especially in the afternoon heading south
- Cooler with snacks and water: No rest stops, and gas station options can be limited between islands
- Phone charger: You’ll want your phone for navigation, photos, and the Monroe County Sheriff app for traffic updates
- Fishing gear (if applicable): If you’re bringing your own rods, Marathon has plenty of spots to use them right away
- Reef-safe sunscreen: Regular sunscreen with oxybenzone is harmful to coral reefs and is discouraged throughout the Keys
- Cash: While most places accept cards, some roadside stands, small attractions, and bridge tolls (if any) may require cash
Arriving at Blackfin Resort & Marina
Blackfin Resort & Marina is located at 4650 Overseas Highway in Marathon, right on the Gulf side at Mile Marker 49.5. As you’re driving south through Marathon, watch for the resort on the right (Gulf) side of the highway. There’s ample parking on-site, including trailer parking for guests bringing boats.
After the drive, you’ll want to do one thing: slow down. Kick off your shoes, walk to the private beach, and watch whatever’s left of the sunset over the Gulf. Then head to the Hurricane Grille for fresh seafood and a cold drink. You’re in the Keys now. The highway can wait.
If you’re bringing a boat, Blackfin’s marina has 27 slips for vessels up to 40 feet, a boat ramp, 30-amp electric, water hookups, and direct Gulf access. Call ahead for slip availability and current rates.
Quick Pre-Trip Checklist
- Book your stay at Blackfin Resort & Marina
- Reserve any attraction tickets in advance (Turtle Hospital, Dolphin Research Center, Aquarium Encounters)
- Download the Monroe County Sheriff’s Office app for live traffic and incident alerts
- Fill up on gas before entering the Keys (prices increase the farther south you go)
- Pack a cooler, sunglasses, reef-safe sunscreen, and a phone charger
- Check weather and traffic conditions the morning of your drive
- Set cruise control to the posted speed limit and enjoy the ride
- Plan at least one stop along the way — the drive is part of the adventure
Ready to hit the road? Book your stay at Blackfin Resort & Marina and start planning your Florida Keys adventure.