The present invention relates to a sediment/water separator used to dredge sediment from the bottom of lakes, rivers, harbors, lagoons, tanks, dykes, reservoirs and seashore. The invention, also named submergible densification cell, dredges sediment of various types at various depths. The sediment can vary as far as their consistency, contamination, stratigraphy, density, origin, concentration, granulometry and other aspects of its formation are concerned. The invention also relates to a sediment densification method which utilizes the submergible densification cell, resulting in an increase of 1.5 to 3 times (by weight) in the concentration of the dredged sediment, reducing the removed volume, the area necessary for deposition, and, as a result, accelerating the open-air drying process of the dredged sediment.