An acoustic detection system for detecting at least partly immersed targets in a sensitive area defined with respect to an infrastructure, characterized in that the system comprises at least one multistatic detection group, each multistatic detection group defining a detection area, and comprising: • A immersed transmitter emitting at low frequencies; • A plurality of immersed receivers comprising at least two receivers, each receiver of a given group forming, with the transmitter of said group, a bistatic pair, each bistatic pair generating an elementary detection area surrounding a blind zone, a blind zone associated to a bistatic pair corresponding to a non-detection zone, the detection area of said group being formed by all of the elementary detection areas of said receivers of the group, said receivers being arranged in at least one layer, the blind zone around each receiver in a given detection group being at least partly covered by the elementary detection areas of the two neighboring receivers of the detection system, and in that, 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 said layer depending on the distance between the transmitter of the group and the rectilinear segment linking said adjacent receivers of the layer, called reference transmitter-receiver distance. • A immersed transmitter emitting at low frequencies; • A plurality of immersed receivers comprising at least two receivers, each receiver of a given group forming, with the transmitter of said group, a bistatic pair, each bistatic pair generating an elementary detection area surrounding a blind zone, a blind zone associated to a bistatic pair corresponding to a non-detection zone, the detection area of said group being formed by all of the elementary detection areas of said receivers of the group, said receivers being arranged in at least one layer, the blind zone around each receiver in a given detection group being at least partly covered by the elementary detection areas of the two neighboring receivers of the detection system, and in that, 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 said layer depending on the distance between the transmitter of the group and the rectilinear segment linking said adjacent receivers of the layer, called reference transmitter-receiver distance. the blind zone around each receiver in a given detection group being at least partly covered by the elementary detection areas of the two neighboring receivers of the detection system, and in that, 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 said layer depending on the distance between the transmitter of the group and the rectilinear segment linking said adjacent receivers of the layer, called reference transmitter-receiver distance.