Cerberus is a blue egg-shaped ultrasound device to detect submerged divers. It is made by Qinetiq. It can distinguish a diver from a seal or dolphin or porpoise. Its range is about 700 metres = 0.435 miles. It was unveiled at UDT2003. It is semi-intelligent and reportedly can detect an air-filled chest cavity underwater and let its operator tell whether the echo is from a man or something irrelevant such as a seal or dolphin, and to distinguish between: a shoal of fish; a ship's wake; a diver with an open-circuit scuba set; a stealth diver with a rebreather; flotsam and jetsam.