Cay

A cay (pronounced key) is a small, low coral island formed by sand and debris piling up on a reef. Different from an atoll, cays are usually linear or scattered along a barrier reef rather than ring-shaped around a lagoon. You'll find them across the Caribbean (the Belize Barrier Reef alone has hundreds), the Bahamas, the Florida Keys, and Australia's Great Barrier Reef. For travelers, the appeal is scale: cays are typically small enough to walk around in 20 minutes, making private island rentals possible. Expect basic infrastructure, boat-only access, and the most pristine snorkeling and free-diving conditions on the planet.