Method for locating threats by using a system, the system being a system for locating threats to a ship, the system having at least a first acoustic sensor and a second acoustic sensor, the first acoustic sensor and the second acoustic sensor being spaced apart physically from each other, the first acoustic sensor and the second acoustic sensor being designed to detect direction-dependent information, a position of a threat being determined from the direction-dependent information from the first acoustic sensor and the second acoustic sensor, each acoustic sensor being designed to detect the direction of origin of sound, the first acoustic sensor having a first monitoring region and the second acoustic sensor having a second monitoring region, and the first acoustic sensor and the second acoustic sensor being arranged such that the first monitoring region and the second monitoring region overlap at least partly in a first overlap region, the system having at least a third acoustic sensor and a fourth acoustic sensor, the third acoustic sensor having a third monitoring region and the fourth acoustic sensor having a fourth monitoring region, and the third acoustic sensor and the fourth acoustic sensor being arranged such that the third monitoring region and the fourth monitoring region overlap at least partly in a second overlap region, the first acoustic sensor and the second acoustic sensor being arranged on the port side of the ship, the first overlap region being arranged on the port side of the ship, the third acoustic sensor and the fourth acoustic sensor being arranged on the starboard side of the ship, the second overlap region being arranged on the starboard side of the ship, the method comprising the following steps: a) receiving an acoustic signal with the first acoustic sensor and detecting the direction A of the received acoustic signal, b) receiving a further acoustic signal with the second acoustic sensor and detecting the direction B of the further received acoustic signal, c) determining the position of a threat from the direction A and the direction B, characterized in that the system has at least one optical sensor (30, 32), and the method also has the steps: d) aligning the at least one optical sensor (30, 32) with the position of the threat determined in method step c), e1) detecting data with the at least one optical sensor (30, 32), e2) determining objects from the data detected in method step e1) by means of image processing programs, e3) determining the object which is located at the position of the threat determined in method step c). a) receiving an acoustic signal with the first acoustic sensor and detecting the direction A of the received acoustic signal, b) receiving a further acoustic signal with the second acoustic sensor and detecting the direction B of the further received acoustic signal, c) determining the position of a threat from the direction A and the direction B, e1) detecting data with the at least one optical sensor (30, 32), e2) determining objects from the data detected in method step e1) by means of image processing programs, e3) determining the object which is located at the position of the threat determined in method step c).