In addition to the extra effort required to distinguish an UXO from the more general TOI (Target of Interest), there is an additional problem faced when the seafloor is littered with a multitude of “junk”: the proximity results in, for electromagnetic sensors and magnetometers, increased response, which is difficult to subtract from the sought-after UXO response. For acoustic systems, it is even worse: the “junk” reflects acoustic energy also, resulting in adding energy to the signal under investigation from unexpected directions and other objects.