Pine Island Sound is a large, shallow saltwater sound in Lee County, Florida, stretching approximately 20 miles from Charlotte Harbor to the Sanibel Causeway. It is a 54,000-acre aquatic preserve situated between the mainland and the barrier islands of Cayo Costa, Captiva, and Sanibel. The water is generally calm and shallow, characterized by vast grassy flats, sandy potholes, and hundreds of small mangrove islands. The paddling environment ranges from moderate to difficult due to open-water distances and exposure to wind and tide, making faster, low-profile sit-inside or sea kayaks recommended for longer crossings. The sound is part of the extensive Great Calusa Blueway paddling trail network.

Access points are numerous around Pine Island and Matlacha. Key launches include the Pineland Monument launch, Kings Landing, Lavendar's Landing, Sirenia Vista Park, Matlacha Community Park, and Castaways Marina. Pineland offers a small beach launch with limited parking, though nearby marinas and preserves offer parking for a fee. Paddlers should confirm public access and any fees at facilities like Castaways Marina. The area retains an "Old Florida" character with few developed beaches, dominated instead by protected mangrove shorelines.

Tidal influence is significant, and paddlers must plan routes considering wind and tide. The sound experiences substantial water movement through the passes along the barrier islands. For the easiest conditions, paddling during slack tide is advised. The open waters are subject to wind, which can create chop, especially over longer fetches. Boat traffic is present, particularly near marinas, channels, and ferry routes to islands like Useppa; paddlers should exercise caution in these areas. A notable open-water crossing of about five miles is required to reach Cayo Costa Beach from Pineland, which should only be attempted on calm days with careful navigation.

Notable features include intricate mangrove tunnels within the Pine Island Sound and Matlacha Pass Aquatic Preserves, where paddlers can explore narrow creeks and saltwater lagoons. Historical sites related to the Calusa Indians are accessible, including the Randell Research Center at Pineland, where paddlers can view shell middens. Wildlife sightings are common and include dolphins, manatees, sea turtles, osprey, eagles, herons, egrets, pelicans, and roseate spoonbills. The water is warm, with an average temperature of 79 degrees Fahrenheit in May. Guided tours and kayak rentals are available from outfitters in Pineland, Bokeelia, Matlacha, Captiva, and Sanibel, catering to both novice and experienced paddlers.