The Poop Deck was the aftermost part of the RMS Titanic. The Third Class passengers didn't have a real promenade, but the Poop Deck served as one.
The Docking Bridge was elevated on this deck, and underneath it was a door leading to the Steering Gear Room. Many benches were placed for passenger use. Overhanging the stern was a flagstaff with a flag of the White Star Line. The forward end of the deck was taken up by 2 cargo cranes. The Poop Deck was 128 feet long. There were skylights for the Steering Gear Room.
When the ship sank, the Poop Deck was the very final deck to submerge. The passengers already realized that the Poop Deck would be the last place to stay dry, so ca. 1100 people gathered there to await the final moment.
The term "poop" comes from the latin word puppis meaning the aft most deck of a ship. Such deck was originally intended to help guard the rear end of a ship from being swamped by large waves. But now ships were much bigger so a poop deck wasn't necessary anymore. The Titanic was the last ship to have a poop deck, it was not included on the Britannic (which was already under construction before Titanic sank) or any other ship later built.
The forward end of the poop deck folded back on itself, exposing the 3rd class public rooms below. The docking bridge pokes out between the bollards and the captain. The area around the capstan has collapsed a few feet which leaves the aft end of the poop deck resting atop the steering gear on C Deck. As of 2019, the poop deck has collapsed.