The dredger can be with a grab or buckets of similar construction as in the land excavator, and it is placed on a special boat or as a portable excavator to the pontoon. There is usually also equipment for the continuous transport of excavated material to the land in the form of a floating conveyor or a floating pipeline. A special type is a suction dredger that extracts sludge, sand and gravel from the underwater bottom by means of a special suction pipe, connected to strong pumps. On the tip of the suction pipe, there is often a jet pump or a rotating nozzle - a rotary head for deepening the soil.
A scraper dredge -a bucket dredge has a scraper or buckets that move over a rope rammed between two towers or pillars over the water. It is used for digging from the water, e.g. for extracting gravel from the river.