A barge is a low boat with a flat bottom that was originally designed to move by being towed or pushed along. Barges were once propelled by pushing them along using a bargepole, or were pulled by a horse walking along the shore. Modern barges are propelled by motors.

A boat is a vehicle that travels over water. Boats may be driven by the wind, by a motor, or by paddling them, like a canoe.

A buoy (pronounced boo-ee) is a brightly colored floating marker that is anchored in place in the water. Buoys can be used to mark where deeper water is in a harbor so ships can safely navigate through.

A catamaran is a type of boat that has two hulls. The hulls are connected somehow, ranging from a simple connection with thin rods to the bulk of the boat forming the bridge.

Catamarans may be either sail or motor powered, and can be any size from tiny sailboats to quite large ships.

A harbor, also spelt harbour, is a sheltered body of water that is deep enough for ships to dock and unload. Harbors are generally an inlet or bay surrounded by land.

A harbor is also a term used for any safe place, or can be used as a verb to mean keeping something or someone safe, as in "he was harboring a known criminal".