The Phantom Ship is a roaming ghost ship in Dragon Quest III. The ship went down many years prior while Eric was caught onboard. Eric's ghost and his Locket of Love can be found onboard, and gaining his locket is essential to reuniting him with his lost lover Olivia to gain entrance to the Shrine Jail.
Finding the ship requires the use of the Boatman's Bone; without which, the ship will never appear to the hero. It's always in the watery areas between Romaria, Asham and Isis. The ship is also featured as one of the boards in Fortune Street.