One of the most amazing sights on a night dive has to be the tiny pinpricks of light in the water as you and your buddies swim through the dark water. This is especially noticeable when your fins and hands splash the surface of the water around you.
What you’re seeing is light caused by bioluminescent plankton.
Plankton is made up of drifting plant and animal organisms in the ocean that are an important source of food for fish and larger marine life such as whale sharks and manta rays.
The most common type of bioluminescent plankton are Dinoflagellates which are tiny, single-celled organisms that emit bright flashes of light when disturbed.
This bioluminescence is also thought to be an anti-predation defence. When Dinoflagellates are attacked by copepods (their natural prey), they flash, alerting shrimps and fish of the copepods’ presence thus turning the hunter into the prey.