A maritime vessel is a type of watercraft used for transportation, fishing, or other activities related to the sea. The most common type of maritime vessel is a SHIP, which is a large vessel that is propelled by one or more engines and sails. An oiler is a smaller vessel that carries fuel oil, lubricating oil, or other petroleum products. Both ships and oilers are essential components of the maritime industry, providing transportation, supplies, and fuel to vessels at sea.