Multibeam sonar systems emit sound waves from directly beneath a ship's hull to produce fan-shaped coverage of the sea floor. These systems measure and record the time elapsed between the emission of the signal from the transducers to the sea floor or object and back again. Multibeam sonars produce a 'swath' of soundings (i.e., depths) to ensure full coverage of an area. Hydrographic data collected from these sonar systems are used to update nautical charts.
<a href="//www.flickr.com/people/40322276@N04" class="extiw" title="flickruser:40322276@N04">NOAA's National Ocean Service</a>
<a href="//commons.wikimedia.org/wiki/Flickr" class="mw-redirect" title="Flickr">Flickr</a>: <a rel="nofollow" class="external text" href="https://www.flickr.com/photos/40322276@N04/4167340394">Collecting Multibeam Sonar Data</a> (Original source: <a rel="nofollow" class="external text" href="http://oceanservice.noaa.gov/images.html">National Ocean Service Image Gallery</a>)