Haunted Castle is a massive ship like island in the Third Sea, known for its dark atmosphere and importance in several late-game activities. It is the third-largest island in the game and has the tallest vertical structure of any map, largely due to its enormous central mast.

Players can locate Haunted Castle by traveling from Castle on the Sea and searching for a flag surrounded by giant walls. Due to recent updates, the island does not render from far away, meaning players need to get fairly close before it becomes visible. This is likely done to reduce lag, since the island is exceptionally large.

One of the most important areas within Haunted Castle is the graveyard, which contains the cemetery and a Gravestone on the left side. Players can pray at the Gravestone to receive random rewards. Inside the mausoleum, players can find Death King, who allows them to exchange Bones for Random Surprises, with up to 10 rolls every 2 hours.