The goal is to survive four missions of differing difficulty without loosing a crew member or the U-boat. Each turn cards are drawn (one at a time) and placed in numbered spaces along an operations track at the top of a board. The crew commander then rolls two die and refers to the card in the space than number represents. If the card does not relate to the current action state of the U-boat. Nothing happens and play proceeds to the next turn and action state.