Sub Bottom Profilers, also known as sub-bottom penetrating sonar, are systems used to identify and characterize layers of sediment or rock under the seafloor. The technique used is similar to a simple echo sounder. A transducer emits a sound pulse vertically downwards towards the seafloor, and a receiver records the return of the pulse, once it has been reflected off the seafloor. Parts of the sound pulse will penetrate the seafloor and be reflected off of the different sub-bottom layers and any objects present. The processing unit then converts these energy flections into a visual image.

Sub-bottom sonar is very useful once a shipwreck has been located.  This instrument allows archaeologists to develop an effective plan for excavation and management of an underwater archaeological location.