Imagine to dive in the dark sea at night close to the reef of Cocos Island, Costa Rica, then suddenly you use the flash of the camera just to have a quick look of the world around you.... that's what you'll see:



Hundreds of Whitetip Reef Sharks hunting.
It could be a relief knowing that they are not aggressive toward humans (normally) and will (generally) swim away if disturbed, although it may bite if harassed. However I would not feel comfortable in the shoes (flippers) of this photographer..