Scuba diver with a school of bigeye trevally or jackfish (Caranx sexfasciatus). Trevally congregate in large schools making it difficult for predators to focus on a single target. Scuba is an acronym for Self-Contained Underwater Breathing Apparatus. Compressed air is held in a tank on a diver's back and breathed in through a mouthpiece. Flippers allow a diver to move through the water quickly and a face mask allows the diver to see while underwater. Diving is a popular pleasure sport. Photographed in Malaysia.