A fireboat is a special purpose vessel whose primary duty is to fight fires.
Early fireboats required crews who were steam-powered, and required crews trained to be mariners. Fireboats use their water cannons to not only fight fires on other vessels, but also to fight fires on docks, and waterfront warehouses. Medium and large fireboats are generally equipped with manifold where land-based fire engines can attach their hoses, so their pumps can supply water when a disaster has been serious enough to rupture a fire department's underground fire mains.
The collapse of the World Trade Center towers, on September 11, 2001, ruptured nearby fire mains, and New York Fire Department firefighters relied on the pumps of their fireboats to supply water pressure.
In recent decades fireboats are likely to have sealed wheelhouses, where crew can use remote control to direct their water cannons, even when the ambient air is dangerous. In recent decades fireboats are likely to have frontline medical facilities to treat victims. In recent decades fireboats are likely to be equipped with tools to contain spills of oil, toxic chemicals, or water contaminated by nuclear, biological or chemical weapons. In recent decades fireboats are likely to be equipped with high-tech sensors, like radar and infrared cameras. The infrared sensor can not only help firefighters locate the hottest, thus most dangerous parts of a fire, but can also be used to help find victims lost at sea, or victims of a man-overboard situation, at night, or when vision in visible light is reduced due to fog or smoke.
In recent decades it has been possible to construct relatively powerful smaller fireboats using propulsion systems similar to high-end recreational craft, that do not require mariners.
Following the September 11, 2001, terrorist attacks the USA's Federal Emergency Management Agency started giving generous grants to equip America's ports with fireboats that are also capable of helping to deal with other natural disasters and terrorist attacks.