Dredging is the excavation of material from a water environment. Possible reasons for dredging include improving existing water features; reshaping land and water features to alter drainage, navigability, and commercial use; constructing dams, dikes, and other controls for streams and shorelines; and recovering valuable mineral deposits or marine life having commercial value. In all but a few situations the excavation is undertaken by a specialist floating plant, known as a dredger.

A body of water, such as a river, canal or lake, is navigable if it is deep, wide and calm enough for a water vessel to pass safely. Navigability is also referred to in the broader context of a body of water having sufficient under keel clearance for a vessel.