Cumberland Sound is a coastal sound and major tidal channel forming the border between Georgia and Florida, separating Amelia Island from Cumberland Island. It is a dynamic saltwater environment characterized by powerful tidal currents, significant wind exposure, and substantial boat traffic, including large vessels and occasional nuclear submarines from the nearby Kings Bay Naval Submarine Base. The sound is considered ACA Level 3 coastal kayaking and is suitable only for experienced paddlers equipped with proper sea kayaks featuring bulkheads, deck rigging, and spray skirts. The primary paddling objective is crossing to Cumberland Island National Seashore, with several launch points available. The most direct but potentially treacherous route is the approximately one-mile crossing from the north end of Amelia Island, specifically from Fort Clinch State Park, to the southern beach of Cumberland Island. This route exposes paddlers to the full force of the sound's conditions, including fast currents, open coastal winds, and a busy navigation channel marked by a large light tower. A longer, calmer alternative is launching from Crooked River State Park in Georgia, paddling east down Fancy Bluff Creek to cross the sound and proceed up the Brickhill River to access the island's central or northern sections. A third option is launching from St. Marys, Georgia. Tidal planning is critical for all routes. Currents are swift, reported to move paddlers up to 8 mph when favorable, and paddling against them is nearly impossible. For trips from Crooked River, paddlers typically launch at high tide to ride the ebb flow to the island and begin the return after low tide to ride the flood back. For the Amelia Island crossing, guided trips schedule departures with incoming tides. The sound's fetch allows for the development of substantial waves, especially with afternoon winds. Hazards include sharp, submerged oyster bars throughout the sound-side waters, which are exposed at low tide and can damage kayaks. Low tide also drains interior marsh creeks, potentially stranding paddlers in mud. Wildlife sightings commonly include dolphins, manatees, sea turtles, eagle rays, and the famous wild horses on Cumberland Island. Paddlers must pay the National Park entry fee for Cumberland Island and secure permits in advance for any overnight kayak camping at designated island docks or campgrounds.