Using sonar, NOAA scientists are able to map huge areas of the seafloor in a relatively short amount of time. The NOAA Ship Nancy Foster has two multibeam sonars that send out three different frequencies of sound. Each frequency allows researchers to map seafloor topography at different depths. The ship sonars also detect "backscatter," which is a measure of the intensity of sound as it reflects off the ocean bottom. This tells researchers if the seafloor is relatively hard (e.g., corals or rocks) or soft (e.g., mud); and smooth or rough. Combining the topography and backscatter data allows scientists to create very detailed three-dimensional maps of the shape of the seaflloor and habitats present on the bottom of the ocean.