Part of the Overseas Heritage Trail and almost entirely inside Curry Hammock State Park, the Grassy Key Trail is a linear paved path under the power lines between Marathon and Grassy Key.
It is hemmed in by tropical forest as it passes through the state park. At the northern end, there are expansive views of the tidal rock barrens surrounded by mangrove forest.
We recommend this as a bike ride as shade is almost non-existent and the mosquitoes can be very, very bad. They are far easier to avoid on a bike.
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Location: Grassy Key
Length: 4.4 miles linear / 6.2 to 8.8 miles round-trip
Trailhead: 24.7413, -80.9972
Restroom: At the picnic area oceanside
Land manager: Florida State Parks
Open sunrise to sunset. Leashed dogs welcome. A campground and picnic area are inside the main gate of Curry Hammock State Park, where fees apply.
There is no shade along this trail. Wind is minimal thanks to dense forests along most of the ride. Insects can be intense at times. Use bug spray if you plan to walk or if you get off your bike.
There are several options for parking to ride or walk this trail. The best bet for cyclists is to use the Grassy Key trailhead along US 1 south of the state park’s main entrance, as access to it is free. If you are camping at the state park or enjoying the day use facilities, you can cycle out of the park and cross US 1 to meet the trail on the bay side.
If you want to start your ride farther south along US 1 to add on another 2.6 miles round-trip (total of 8.8 miles), park at the large bayside parking area on Marathon that adjoins the Overseas Heritage Trail, the Key Vaca Wayside.
There are two possible starting points for this ride. The one that most visitors use is the Grassy Key trailhead. It allows for a 6.2 mile round-trip along the most scenic part of the trail.
Alternatively, starting at Key Vaca Wayside at Marathon adds another 1.3 miles each way for an 8.8 mile ride. That 1.3 miles, however, directly adjoins US 1.
It’s a pleasant ride either way, so your starting point depends on planned mileage.
The trail sits under the power lines, so there is no shade to speak of. It’s a straight line off into the distance.
However, the saving grace of this trail north of the Grassy Key trailhead is the screen of tropical forest between it and US 1.
It helps muffle road noise and makes for a nicer view. It also provides habitat for many species, and it harbors a few plants that you should avoid brushing against.
Just a little north of the trailhead, a small rest stop with benches sits next to the trail.
Stop here to see the overview map and, on the back of the kiosk, information about habitats you’ll see along this route.
Pass the turnoff for the Curry Hammock Nature Trail at a kiosk on the left. You’ll pass a limerock road on the right, as well.
Cross a paved road across US 1 from the main entrance to Curry Hammock State Park.
By 1.3 miles, a tidal rock barren on the bay side comes into view along Florida Bay. Portions of it have taken over by invasive species like Australian pine.
The rocks are white and chalky, with some interspersed mangroves and bay cedar. Pass by a power substation with a limerock road leading to it.
At 2.5 miles, Cross Kyle Avenue. It leads back to some homes. The trail curves soon after.
There is a bench and a place to walk down into the tidal rock barren for views across the mangrove-lined salt ponds.
While it was quite pretty on our first visit, the mangroves were pretty roughed up after Hurricane Irma.
The trail ends just past Guava Avenue, which is at 3 miles. At this stop sign, the bike route sign directs riders out onto US 1.
If you’re headed northbound on the Florida Keys Overseas Heritage Trail, you’d cross US 1 to the northbound bike lane and continue along that route.
You can continue a short distance north of Guava Ave on the Grassy Key Trail but it abruptly runs out of pavement. Don’t keep going into the woods.
Turn around and return to the Grassy Key trailhead for a round-trip ride of 6.2 miles, or the Key Vaca Wayside for an 8.8 mile ride.
The Grassy Key Trail is part of both Curry Hammock State Park and the Florida Keys Overseas Heritage Trail. Learn more about both.
Bring your binoculars for fall birding at Curry Hammock State Park, where migrating raptors cruise overhead by the hundreds following a major flyover route.
For hikers, this trail also allows you to make a loop on the Curry Hammock Nature Trail, using the same trailhead as your starting point.
See our photos of the Grassy Key Trail
More worth exploring while you’re in this area.
Part native, part cultivated, Crane Point Hammock is 63 acres of tropical hardwood hammock in the heart of Marathon. Preserved from development in 1989 by the Florida Keys Land Trust, it is the largest tropical hammock in the Middle Keys.
At the southern tip of Marathon, Sombrero Beach offers beachgoers a natural strand and an easy beach walk within sight of the Keys’ largest lighthouse.
Spanning shore to shore across much of its namesake island, Long Key State Park offers a bounty of botanical wonders across a variety of rare Florida Keys habitats.