When hundreds of eerily perfect circles were discovered on the bottom of the Mediterranean Sea, theories abounded about what they could mean. Four years of underwater research revealed a lost world.

In the depths of the ocean, a colossal blue hole has been unveiled ... From an aerial perspective, they appear as dark blue circles amidst lighter surrounding waters. The formation of these ...

Explore 5 locations worldwide where bioluminescent marine organisms illuminate the ocean, creating a glowing effect.

This is only the second time the species has been recorded while alive. “I thought it was A.I.,” says fish biologist Kory Evans.