Ah, great question, I can see you're a fan of the series! In 'Pirates of the Caribbean: Dead Man's Chest', Will Turner becomes the captain of the Flying Dutchman, a ghostly ship, after his father. According to the curse of that ship, The Flying Dutchman must always have a captain. Therefore, as the captain of the Flying Dutchman, Will Turner needs to ferry the souls of those who died at sea to the afterlife. The barnacles on his face signify his bond with the ship and the sea.