Look west from the end of Marathon and the road simply leaves land behind. The Seven Mile Bridge starts here, carrying US 1 across open water toward the Lower Keys, and beside it runs the old bridge, built in the early twentieth century for Henry Flagler's Overseas Railroad, which reached Key West in 1912. A hurricane on Labor Day 1935 wrecked the railway, and the line was converted into a highway. Part of the old bridge is now a path for walkers and cyclists, leading out to Pigeon Key, where the workers who built the bridge once lived.
Marathon is the main town of the Middle Keys, a string of islands with a population of several thousand that grows in winter with snowbirds and boaters. It is a working town as much as a resort, with marinas, fishing boats, shops and an airport. Its name supposedly comes from the railway workers, who described the relentless job of building across these islands as a marathon. Here you will find every service: fuel, restaurants, groceries, hotels and a hospital.
The riding along the Keys is not about corners. It is about light and water: the road runs straight, almost flat, on causeways and bridges with the Atlantic on one side and Florida Bay on the other, and the colours range from deep blue to pale turquoise over the shallows. Wind is the main factor; crosswinds on the bridges can be strong, and summer storms build quickly in the afternoon. Speed limits are low and strictly enforced on many sections, and the traffic in season can be slow and heavy. Ride early in the morning, when the light is soft and the road is quiet.
There is plenty to see if you stop. The Turtle Hospital rescues and treats injured sea turtles, and you can visit on a guided tour. Crane Point preserves a slice of tropical hardwood hammock with trails and a small museum. Sombrero Beach, on the ocean side, is one of the nicest beaches in the Keys for a swim. Fresh fish, stone crab in season and Key lime pie are the local foods. From June to November, check the hurricane forecast before you commit to the Keys, since there is only one way in and out.