The aim with the project "distributed detection" is to enable surveillance of areas at sea, as well in harbour and in costal areas. The background is that the underwater activities are getting more and more silent and can vary from traditional submarines, to UUV:s and divers. The needs are also changing from stationary equipment to rapidly deployable. In the project a detection and tracking algorithm for distributed communicating sensors spread over the surveillance area, has been developed. In the report at hand, the concept with simple wirelessly communicating sensor nodes under water is presented. Performance for the algorithm, which has been developed, has been simulated for a few cases. As is clear, with a large probability it is possible to detect relatively quiet submarines, with a distance between nodes of a few hundred meters. The report is concluded with recommendations about future activities in the area.