Looking like giant leaves floating in the sea, thousands of Golden Rays are seen here gathering off the coast of Mexico, off the northern tip of the Yucatan Peninsula, gliding silently beneath the waves, turning vast areas of blue water to gold.
These magnificent creatures are making one of their biannual mass migrations to more agreeable waters.
The spectacular scene was captured by Sandra Critelli, an amateur photographer, stumbled across the phenomenon while looking for whale sharks.
'It's hard to say exactly how many there were, but in the range of a few thousand'
Despite having poisonous stingers, they are known to be shy and non-threatening when in large schools.
Contributed by: Estrelita Soliano Grosse.