In naval architecture an afterdeck or after deck or sometimes the aftdeck or aft deck is the open deck area toward the stern or aft back part of a ship or boat. The afterdeck can be used for a number of different purposes. Not all ships have an afterdeck. In place of the afterdeck a ship may be built with a poop deck, that is a deck that forms the roof of a cabin built in the rear, or "aft", part of the superstructure of a ship. A poop deck usually is higher up than an afterdeck. A ship may have its superstructure or aftercastle located in the stern and thus not have an afterdeck. The stern and afterdeck of a ship are usually more smooth and stable than the bow (front) of the ship in motion. A taffrail is the handrail around the open afterdeck or poop deck. On wooden sailing ships like man-of-war or East Indiaman the taffrail is usually a hand carved wood rail and often highly decorated.  
- Navy war ships may use the afterdeck to mount deck guns.
- Missile boats may have missiles launching on the afterdeck.
- Minelaying gear on Navy ship's afterdeck.
- Minesweeper gear on Navy ship's afterdeck.
- Depth charge launching on Navy ship's afterdeck.
- Torpedo tube for torpedo launching on Navy ship's afterdeck.
- Some Navy and private ships use the afterdeck as a helicopter deck for a heliport for helicopters.
- A sundeck for chairs, chaise longue and lounge chairs.
- Rear deck swimming pool with a sundeck.
- On fishing boats a place to lay fishing nets or big-game fishing chairs or trawler gear.
- Cable laying gear.
- Scuba diving deck.
- Amphibious vehicle launching
- Submersible launching
- Water skiing launching
- Samson post, a strong pillar-post for a towing cable or other support.
- Lifting Crane or gantry crane.
- Ferry ramp for vehicles.
- Ancient Greece ships sometimes had shrines or altars on the afterdeck.
HMNZS Canterbury (L421) with a large aftdeck for helicopters.
HMNZS Canterbury (L421)'s helicopter afterdeck.
President Truman and members of his staff relaxing on the afterdeck of the yacht USS Williamsburg.
After deck of USS Manchester (LCS-14).
After deck of the Abeille Bourbon.
Sailors on the afterdeck of the HTMS Nakha.
Aftdeck pool on the Golden Princess.
After deck of a UK Rescue Lifeboat 17-31.
- Getty Images, Taffrail Pictures and Images
- http://phrontistery.info, Nautical Terms
- Yachting, Dec. 2006 issue, page 94
- US Navy, LPD 17 Program Summary, Jan. 2017
- Marine Technology, Vol. 18, No. 1, Jan. 1981, pp. 38-50 Motion Studies of a Vessel with Water on Deck by Jeff Dillingham
- The Greek Age of Bronze Ships