How the aggregation works
Hanifaru Bay functions as a plankton trap. The bay's shallow floor and surrounding reef structure cause incoming tidal currents to concentrate surface zooplankton into a dense feeding zone. Manta rays — both the oceanic species (Mobula birostris) and the reef species (Mobula alfredi) — follow the plankton, entering the bay in coordinated barrel-roll feeding formations that allow them to cycle through the densest patches. The aggregation is entirely tide and plankton dependent. A strong bloom on an incoming tide can bring over 200 mantas into a space of a few hundred metres. A low-plankton day at the same tide may produce fewer than a dozen. This variability is why time spent in the atoll — rather than a single day-trip window — is the strongest predictor of a peak encounter.
