Up to 200 reef manta rays feeding at once in a bay the size of a football pitch, barrel-rolling through plankton soup with…Up to 200 reef manta rays feeding at once in a bay the size of a football pitch, barrel-rolling through plankton soup with mouths wide open, sometimes joined by whale sharks. Scuba is banned so it's all on one breath, in 5m of water, with mantas passing inches away. A tidal cul-de-sac where the monsoon current traps plankton against the reef. Photographer Guy Stevens documented the aggregation in 2009, it became a UNESCO Biosphere core zone in 2011, and strict permit caps were imposed after early free-for-all years nearly wrecked it. Anchorage: Anchor outside the protected bay; ranger permit and licensed guide mandatory, timed entry slots. Hazards: No site-specific hazards noted, brief normally. Plus