Sonar stands for Sound Navigation and Ranging. Sonar has been used extensively at sea to chart the oceans, locate hazards, search, and more. Sonar uses sound waves because sound waves travel farther in water than radar or light. Active sonar pulses sound waves into objects and “listens” for echoes that can help map the investigated area. Passive sonar involves “listening” for sound waves in the ocean, such as other boats or whales.