A deck is a permanent covering over a compartment or a hull of a ship. On a boat or ship, the primary or upper deck is the horizontal structure that forms the "roof" of the hull, strengthening it and
RMS Olympic's deck
The upper deck of the Falls of Clyde is iron; a centre strip is planked with wood as a sort of walkway. As is typical for a late-19th-century vessel, several deckhouses may be seen.
Crew and passengers on the wraparound deck of RMS Queen Mary 2, an ocean liner
Weather deck of the Swedish 17th-century warship Vasa looking aft toward the sterncastle
The forecastle is the upper deck of a sailing ship forward of the foremast, or, historically, the forward part of a ship with the sailors' living quarters. Related to its latter meaning is the phrase
Deck (ship)
…Flush deck: Any continuous unbroken deck from stem to stern. Forecastle deck: A partial deck above the main deck under which the sailors have their berths, extending from the foremast to the bow. Freeboard deck: assigned by a…
Replica of the Victoria, the only one of Ferdinand Magellan's five ships to return to Spain in 1522, showing its forecastle (left/foremost), quarterdeck (middle right), and poop deck (far right/aftmost).
The forecastle of RMS Queen Elizabeth 2
Foredeck of Severn-class lifeboat No. 17–31 at quay in Poole Harbour, Dorset, England.