Tugboat, or tug, is a boat used to manoeuvre, primarily by towing or pushing other vessels in harbours, over the open sea or through rivers and canals. They are also used to tow barges, disabled ships, or other equipment like towboats. A tugboat can also refer to a recreational boat that resembles a tug in shape but is not capable of or designed for towing. Tugboats are highly maneuverable due to their propulsion units.