Optimised acoustic detection system for detecting various underwater threats in a sensitive zone

An acoustic detection system for detecting at least partly submerged targets in a sensitive area defined with respect to an infrastructure, the detection system includes at least one multistatic detection group, each multistatic detection group defining a detection area, and comprising: a submerged transmitter emitting at low frequencies; a plurality of submerged receivers comprising at least two receivers, each receiver of a given group forming, with the transmitter of the group, a bistatic pair, each bistatic pair generating an elementary detection area surrounding a blind zone, the detection area of the group being formed by all of the elementary detection areas of the receivers of the group, the receivers being arranged in at least one layer. For at least one group of the system, the form described by the receivers of at least one layer of the group is an at least partly circular form of given radius, the inter-receiver distance between two adjacent receivers of the layer depending on the distance between the transmitter of the group and the rectilinear segment linking the adjacent receivers of the layer, called reference transmitter-receiver distance.