Many have taken to Instagram to share incredible photos and videos of the bright blue glow which is caused by billions of single-celled algae or plant plankton.

Noctiluca, more commonly known as sea sparkle, is one example of bioluminescent algae. They are so small thousands of them can fit in a drop of water. 

Glow-in-the-dark plankton can glow blue, green, red or orange.

Noctiluca use energy to help them glow. They don’t glow during the day to preserve that energy. 

It is understood that the glow is used to scare away predators, but could also attract bigger predators.