Marathon is a city in Florida located in the Florida Keys, with the Atlantic Ocean on one side and the Gulf of Mexico and Florida Bay on the other. It is on somewhat of a long narrow island . You will find all of the amenities of a small town that includes an excellent hospital, shopping and small airport. Mosquitos are less common than in some parts of the Keys, as they spray them. The waters are warm, clear and inviting. If you are visiting the Florida Keys, Marathon is a great choice to make your base. Marathon has more of a permanent population than some of the other Keys and a good base of services.