A trailing suction hopper dredger operates very much like a floating vacuum cleaner. It pumps up materials from the sea floor and then discharges them into a storage compartment known as the hopper. After filling up its hopper, the dredger then sails to the disposal site where it unloads its cargo. These machines are used to rehabilitate dying beaches, fortify riverbanks, recontour ports and harbors, construct offshore multi-terminal airports, etc.
From Pruned blog