1. A group of vessels having an unmanned surface vessel and an unmanned autonomous underwater vessel, wherein the surface vessel has a drive and a control device, which is arranged in such a manner that the surface vessel is steered with regard to the autonomous underwater vessel taking the behavior of the autonomous underwater vessel into account, and the autonomous underwater vessel comprises a sonar device, for sensing location data in the underwater area and one or more evaluation units, the evaluation units arranged in such a manner so as to include a detection device for detecting a contact (MILEC) by the sensed location data, and a classification device for classifying the detected contact (MILEC) as a mine-like contact (MILCO) or a non-mine-like contact (NONMILCO), wherein the classification is accomplished by comparing the contact (MILEC) with known mine information so that a mine-like contact (MILCO) can be identified as a mine contact (MINE) or as another object (NOMBO) and an area of sea can be autonomously cleared.