Deans Blue Hole

Dean's Blue Hole is a natural marine sinkhole forming a dramatic vertical shaft that plunges to about 663 feet from a roughly 82–115 foot wide surface pool next to a white sand beach, widening to roughly 328 feet in diameter below about 66 feet. The site is noted for very clear, calm water and steep limestone walls often described as a "blue cathedral"; the upper 33–66 feet feature hard limestone ledges and coral outcrops that support reef fish and invertebrates. Divers enter from the beach (shore entry) and descend from the surface pool, typically along a descent line or rope. Conditions inside the hole are usually sheltered with minimal currents; surface temperatures are typically about 75–88°F and visibility is often excellent, commonly about 33–98 feet or more on clear days. Recreational dives commonly explore ledges and reef structures to roughly 66–98 feet, while technical divers may continue to deeper ledges (for example around 115 feet) and beyond using mixed gases and staged decompression. Hazards are significant due to the extreme depth: rapid increases in decompression obligations, risk of nitrogen narcosis and oxygen toxicity, steep disorienting walls and no overhead exits; advanced or technical certification and appropriate equipment (dive computer, redundant air, proper gas mixes and staged decompression procedures) are recommended, and a local guide is advised given the site's remoteness.