Colón is a sea port on the Caribbean Sea coast of Panama. The city lies near the Atlantic entrance to the Panama Canal. It is capital of Panama's Colón Province and has traditionally been known as Panama's second city. Colón was originally located entirely on Manzanillo Island, surrounded by Limon Bay, Manzanillo Bay and the Folks River. Since the disestablishment of the Canal Zone, the city's limits have been redefined to include the former Canal Zone towns of Cristobal, Rainbow City, Margarita, and Coco Solo, as well as the former U.S. Army base of Fort Gulick.