Play, Relax, Explore - it's all here for you at Cumberland HarbourCumberland Harbour is set on a 1,100 acre maritime peninsula surrounded by the St. Marys River, The North River, and the Intercoastal Waterway with direct access to the Atlantic Ocean and Cumberland Island National Seashore. Designed with nature in mind, Cumberland Harbour is a delight to the senses. Experience why Cumberland Harbour is the ideal place to play, relax and explore.