We're well aware that the ocean is an extraordinary and mysterious place, but for William Mitchell, a scuba diver from London, one particular plunge in Grand Cayman turned into a once-in-a-lifetime experience.
In July 2013, Mitchell was diving in the Devil's Grotto, an undersea cavern, when he encountered a massive cloud of Atlantic silversides -- a phenomenon known in the dive community as a "silver rush."
His footage, which was recently re-edited and posted by GoPro, shows what Mitchell described as "a wall of solid silver." A ton of fish dart around him in incredible harmony, and the dense school parts in sync to make way for him.
Mitchell, now 24, said that the experience was nothing short of amazing. "It is very difficult to put into words how it felt diving with all those tiny fish," he told The Huffington Post.
It's understandable -- swimming through an underwater ballet of liquid silver seems to warrant speechlessness.