A long exposure renders bar jacks (Carangoides ruber) as ghostly trails as they swim around a sponge, on a coral reef, at night. East End, Grand Cayman, Cayman Islands.
Explanation: this photo is a long exposure showing predatory fish hunting over a coral reef, the long exposure rendering the fish like swirling phantoms against the inky, black sea. On the right you can see the outline of one fish as it stops to feed, its trail showing how it swooped down, across the frame to catch its prey. Around the central reef sponge you can even see the trails of the smaller fish and zooplankton that the jacks were hunting. The longer you look, the more you see.