The term 'deck opening' refers to openings in the deck of a ship or boat. The most common deck openings are hatches, which are typically square or rectangular and are used for access to the interior of the vessel. A SCUPPER is an opening in the side of a ship that allows water to drain off the deck. A HATCHWAY is a larger opening than a HATCH, usually located at the base of the mast, and is used for access to the lower decks.