Britannica
Sources used in this answer
How is sonar used to find fish, shipwrecks, and underwater hazards?
Created from Britannica articles
using AI.
AI can make mistakes, so verify using Britannica articles.
undersea exploration
Learn about the pioneering life and work of American oceanographer and explorer Sylvia Earle.
Sonar—an acronym for "sound navigation ranging"—detects underwater objects by analyzing acoustic waves.1
How Sonar Works
- Active Sonar: A projector emits sound waves that reflect off objects. A receiver captures these echoes to determine the target's range, bearing, and motion.1
- Passive Sonar: Sensors detect noise produced by objects, such as ships or submarines, to identify their location.1
Applications
- Finding Fish: Specialized fish-finders use high-frequency sonar to locate schools of fish. Simple echo sounders point downward to detect fish and water depth, while complex scanners transmit signals in all directions to cover wider areas.2
- Detecting Hazards and Shipwrecks: Echo sounding measures the time it takes for a pulse to reflect off the seabed, revealing depth and identifying objects like rock pinnacles or shipwrecks. Side-scan sonar is particularly effective for mapping the ocean floor and identifying dangerous underwater obstructions to the side of a vessel's path, allowing for detailed surveys of potential hazards.34