Colón is a city and seaport in Panama, beside the Caribbean Sea, lying near the Atlantic entrance to the Panama Canal. It is the capital of Panama's Colón Province and has traditionally been known as Panama's second city. Originally it was located entirely on Manzanillo Island, surrounded by Limon Bay, Manzanillo Bay, and the Folks River; however, since the disestablishment of the Panama Canal Zone, the city's limits have been redefined to include Fort Gulick, a former U.S. Army base, as well the former Panama Canal Zone towns of Cristobal, Margarita, and Coco Solo.