Marathon is a city in the middle of the Florida Keys, in Monroe County, Florida, United States. As of the 2020 census, the city had a population of 9,689, up from 8,297 in 2010. Though the area has been settled for some time, Marathon is a relatively new city, incorporated in 1999.
AdChoose from the Largest Selection of Fishing Guides in Marathon. View Now! Easy Online Booking. Verified Captains. Flexible Cancellation. Real Customer Reviews.