US Navy bottlenose dolphin (Tursiops truncatus) leaping out of the sea in the Arabian Gulf. This dolphin was trained at the Navy Marine Mammal Program (NMMP), San Diego, USA. A transponder attached to the pectoral fin allows handlers to track the dolphin's location. Dolphins have been trained by the US Navy since the 1960s for a variety of underwater tasks including, locating underwater mines, delivering equipment, locating objects, surveillance and guarding against human intruders. Dolphins are highly intelligent animals and proficient swimmers, using echolocation to sense their surroundings. The NMMP also trains California sea lions, killer whales and beluga whales.