System for dredging underwater sea-bed comprising : - a platform provided with flotation means, a dredging tool being provided on the portion of said platform facing the surface of the water, provided with means suitable for lowering and lifting it, and being provided with at least three connection points associated with said platform, for connection to the ends of respective warping cables, suitably anchored to the shore at the opposite ends, and provided with suitable tensioning means; sediment collection means collected by the dredging tool, means for detecting the absolute position of said platform; means for detecting the position of said dredging tool; - means for detecting the seabed configuration; - means for detecting the quantity of sediment removed from the seabed; remote command and control means of said means suitable for lowering and lifting said dredging tool, tensioning means for the warping cables, and all detection means; - means for supplying the equipment on board the platform.