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The Abandoned Ship lies in the sea between Dewford Island and Slateport City. Enter it and keep using your Itemfinder to collect fallen items which include the keys to various doors of the ship. You will also find the only Luxury Ball of the Game here. This Pokéball ensures that the Pokémon captured will be friendly. Remember not to use it on any Pokémon, as this is the only easy way to catch the Legendary Pokémon Regice.