What is an Atoll?
An atoll is a ring of coral that originally grew completely around the shoreline of an island, and which continued to grow upward on top of itself as the island subsided or eroded away. The ring reef we see today at Glover Reef outlines the shoreline of an ancient island (call it Glovers Island) that once existed at this location. This island was exactly the size and shape of present day Glovers Reef Atoll, today an oval ring of coral 54 miles in circumference surrounded by the Caribbean Sea.
This Belize atoll was formed about a million years ago. Much much more recently, say approximately 1000 years ago, four tiny islands formed atop the reef ring of the atoll. They are all located on the windward side of the atoll, and are the result of hurricanes breaking coral and piling it up on the reef. The islands of Glover’s Reef are, from north to south, Northeast Caye, Long Caye, Middle Caye, and Southwest Caye.