Ghost ship

A Ghost Ship in terms of reality is a ship that is seen sailing the sea without a crew. In real life, there are cases where crews go to sea and something would happen to them (for example, they all die), leaving their ship wondering alone on the waves. Accounts of ghost ships still occur today, though usually on small vessels where the crew has perished at sea through one reason or another.

In terms of fiction, a ghost ship is a vessel that is regarded as haunted, usually by the ghost, skeletons or zombies of her dead crew. The stereotype of a ghost ship is a vessel that seem unfit to float at sea yet despite its unsightly appearance is capable of floating on the sea as if it was not. Often they are portrayed as evil or cursed vessels and are feared by many who come across them.

One Piece
Several ghost ships have been encountered by the Straw Hat Pirates during their journey at sea. One ghost ship was a massive one that fell from the sky several hundreds of years after the death of its crew. The ship, who's origin was identified as the kingdom of St. Briss, was eventually investigated by the Straw Hat's and a salvage team lead by Mashira, leading to the Straw Hats to eventually head towards the White Sea and discover the mysteries of the land of Skypiea.

Another ghost ship was encountered upon entrance in the Florian Triangle. This ship was the former ship of the Rumbar Pirates, where all of its crew were dead outside one: the former captain and musician Brook, who lived alone due to the power of his Yomi Yomi no Mi reviving him after his death.

Immediately after encountering the Rumbar ship, the Straw Hats encountered a "literal" ghost ship called Thriller Bark. Lead by Shichibukai member Gekko Moria and his Mysterious Four, the ship was home to a menagerie of creatures including zombies revived by his Kage Kage no Mi and ghosts created from the Horo Horo no Mi of crewmate Perona. Aside from Moria and Perona, Absalom and Doctor Hogback were the only literally living beings on the ship aside from all the victims, zombies and ghosts.