This is an interesting explanation about the performance of the echolocation system of dolphins to detect remote objects or animals and even find them beneath the sand, regardless if they are camouflaged.

When using echolocation, dolphins emit a series of sounds in the form of bursts that “bounce” or return as echoes which they detect, and allow them to measure the distance and the size of the object or animal. Undoubtedly, dolphins are one of the most intelligent species on our planet and above all, one of the most studied by researchers.