Sardines emerge from a coral wall in cobalt waters just a few yards from the shores of Cebu Island in the Philippines. They move in a single undulating cloud of silver that twists, turns, shrinks, expands and wraps itself around any object that gets in its way. At times, it becomes a thundercloud, blocking out the sun or clapping violently as it suddenly flips its formation to evade a predator.

This photo is a finalist in the Natural World category of our 15th Annual Photo Contest. See all 60 finalists here.