Marathon is a bustling town, at least compared with other Keys communities. If you get off the main drag, you'll find the few oceanfront hotels, but there are a number of good dining options right on Overseas Highway, so you'll definitely want to stop for a bite even if you're just passing through on the way to Key West.
If you stop a while, you’ll find Marathon has the most historic attractions outside of Key West, and the well-worth-visiting Sombrero Beach—though fishing, diving, and boating are the main events here. The town throws tarpon tournaments in April and May, more fishing tournaments in June and September, a seafood festival in March, and lighted boat parades around the winter holidays.
New Englanders founded this former fishing village in the early 1800s. The community on Vaca Key subsequently served as a base for pirates, salvagers (also known as "wreckers"), spongers, and, later, Bahamian farmers who eked out a living growing cotton and other crops. More Bahamians arrived in hopes of finding work building the railroad. According to local lore, Marathon was renamed when a worker commented that it was a marathon task to position the tracks across the 6-mile-long island. During the building of the railroad, Marathon developed a reputation for lawlessness that rivaled that of the Old West. It’s said that to keep the rowdy workers from descending on Key West for their off-hours endeavors, residents would send boatloads of liquor up to Marathon. Needless to say, things have quieted down considerably since then. Grassy Key segues into Marathon with little more than a slight increase in traffic and higher concentration of commercial establishments. Marathon's roots are anchored to fishing and boating, so look for marinas to find local color, fishing charters, and good restaurants. At its north end, Key Colony Beach is an old-fashioned island neighborhood worth a visit for its shops and restaurants. Just be warned the police are plentiful and love to catch speeders. Nature lovers shouldn't miss the attractions on Crane Point. Other good places to leave the main road are at Sombrero Beach Road (MM 50), which leads to the beach, and 35th Street (MM 49), which takes you to a funky little marina and restaurant. Overseas Highway hightails through Hog Key and Knight Key before the big leap over Florida Bay and Hawk's Channel via the Seven Mile Bridge.