Backpacking beachcombers never see the same Cumberland Island twice: Shifting sand dunes turn the 17.5-mile-long national seashore into a constantly changing wilderness, where wild horses roam the sea grass, armadillos poke through the palmettos, and turtles nest throughout the summer. Backcountry campsites dot the northbound hike, with Stafford Beach (3.5 miles from the ferry dock) a short walk from the ocean and Brickhill Bluff (10.6 miles) about an hour's walk from the Atlantic. Reserve early, and bring a jar of horseradish – there are oyster beds to explore as the sun dissolves into the western marshes. [camping fee $4 a night;]