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A multibeam echosounder is a type of sonar that is used to map the seabed. Like other sonar systems, multibeam emit sound waves in a fan shape beneath a ship's hull. The amount of time it takes for the sound waves to bounce off the seabed and return to a receiver is used to determine water depth. Unlike other sonars, multibeam systems use beamforming to extract directional information from the returning soundwaves, producing a swath of depth readings from a single ping.

Multibeam bathymetric systems in the marine biology field have two functions:

• provide the necessary information to the planning without the safety limits of the side scan sonar investigations involving the use of tools to tow the boat.
• from the multibeam surveys it is possible to obtain informations on the morphology of the seabed and therefore directly on the nature of the site.

The bathymetric systems with multibeam technology allow to acquire continuously, and with excellent precision, bathymetric profiles at the same time and therefore to detect a strip of seabed (transversal to the direction of travel of the vessel) with an amplitude that varies according to the type of multibeam system used as well as the depth at which it operates.