The Papa is a blue square with a white square in the middle. When the flag is displayed it means the vessel is about to sail. This flag has been used to bring divers back to the surface and discontinue diving operations. When the flag is up, the tenders realize the end of diving has been signaled and start the divers toward the surface. Sometimes large cruise ships will tell their departing tourists to return to the ship when the Papa flag is hoisted to the top of the vessel.