This is the once-in-a-lifetime moment a swimmer caught on camera a 2,000-strong shoal of rare migrating rays.
Conservationist Jay Gittens, 44, initially thought the enormous 'shadow' below the surface was a whale shark or humpback whale.
Amazed Jay slipped into the water off La Paz, Mexico, and freedived with the enormous group of Pacific cownose rays.
While the eagle rays are not endangered, it is rare to capture such a large group moving together.
Quick-thinking Ray, from London, clicked on his Go Pro camera and captured staggering photos and footage.
Jay, who works with conservation project Whale Shark Diaries, said it was his "number one best wildlife encounter".