Great Wall (Bloody Bay)

The Great Wall is Bloody Bay's thesis statement. You cross a strip of bright sand in snorkel depth, and then the island simply stops: a face so vertical that looking down produces the small electric lurch of standing on a rooftop ledge. The wall's skin is packed (vase sponges, wire corals, tunicate constellations), and its shallow start means the spectacle works at any depth you choose, including from the surface with a mask. Groupers escort divers along the lip; turtles fly past below like commuter traffic. Few walls anywhere begin so shallow and end so absolutely.

The moment you come for: A sheer face beginning at 6 m, sponge-packed vertical terrain, wall scenery accessible even to snorkelers.

Topography: The reef shelf ends at about 6 m in a wall that drops vertically, undercut in places, into abyssal blue.

Entry: Moored inside the marine park; a short swim crosses the sand shelf to the lip.

Hazards: The shallow lip hides an instant transition to great depth; set and hold a floor.

Conservation: Bloody Bay Marine Park is mooring-only with strict no-take rules; its condition is the argument for them.

Nitrox: Worth it here: profiles sit in the range where enriched air meaningfully extends no-stop time (with the training to use it).