This is the once-in-a-lifetime moment a British swimmer caught on camera a 2,000-strong shoal of rare migrating RAYS.<br /><br />Conservationist Jay Gittens, 44, initially thought the enormous 'shadow' below the surface was a whale shark or humpback whale.<br /><br />Amazed Jay slipped into the water off La Paz, Mexico, and freedived with the enormous group of Pacific cownose rays.
