At port areas, a wide-angle underwater imaging system has been in strong demand for wide-range inspections of undersea-structures for periodic maintenance and for rapid check in case of disaster-affected. However, seawater in such areas is often turbid due to urban activities, which makes underwater imaging more difficult. Thus, we developed a prototype of three-dimensional sonar system 07 (hereinafter called System 07) with surveying support feature for portside underwater constructions. System 07 was used in a water tank, and its image performance was experimentally measured for a 6 m x 6 m field of view, with 0.1 m x 0.1 m x 0.13 m spatial resolution at an approximately 10-m range. In addition, System 07 successfully acquired acoustic images for a 1-mm-thick H-shaped aluminum plate target 1.4 m wide and high at approximately an 11-m range.