You duck under an overhang and surface inside a limestone dome with holes in the roof dropping shafts of light onto the water…You duck under an overhang and surface inside a limestone dome with holes in the roof dropping shafts of light onto the water, and thousands of sergeant majors swirling around you. Multiple entrances, coral on the walls, and the light show peaks at midday. The best snorkel in the Exumas. Named for the 1965 Bond film 'Thunderball', which was filmed inside it; 'Never Say Never Again' and 'Splash' used it too. The grotto has been the single biggest draw of the central Exumas ever since, and it is still free, unticketed and reached only by your own tender. Anchorage: Anchor off Staniel Cay in 3-6m; the grotto is a short tender ride. Staniel Cay Yacht Club has dockage. Hazards: No site-specific hazards noted, brief normally. Plus