Underwater detection system

A transducer array is driven to generate a first transmission wave of narrow beam width and a second wave of wider beamwidth. A reception circuit receives reflected waves corresponding to each of the first and second transmission waves, and generates respective reception signals. First and second image generators process those signals to generate images based, respectively, on reflections corresponding to the first and second transmission waves. The first and second images may respectively be 2D or 3D images, where the 3 dimensional image may be a projection of three dimensional data onto a plane (horizontal, vertical, or otherwise inclined) such as top and bottom views representing projections upwards or downwards from the data. The 3D image may include several projections. Processing apparatus 5 may be remote from the sensor array, and data transfer and processing operations of that apparatus may take place in parallel with generation of the first image.