High Quality Content by WIKIPEDIA articles! Active sonar, the transmission equipment used on some ships to assist with navigation, has been suggested to be detrimental to the health and livelihood of some marine animals, although the precise mechanisms for this are not well understood. Some marine animals, such as whales and dolphins, use echolocation or "biosonar" systems to locate predators and prey. It is conjectured that active sonar transmitters could confuse these animals and interfere with basic biological functions such as feeding and mating. A recent study has shown that whales experience decompression sickness, a disease that forces nitrogen into gas bubbles in the tissues and is caused by rapid and prolonged surfacing. Although whales were originally thought to be immune to this disease, sonar has been implicated in causing behavioral changes that can lead to decompression sickness.