There are many reasons why underwater archaeology can make a significant contribution to our knowledge of the past. In the shipwreck field alone, individual shipwrecks can be of significant historical importance either because of the magnitude of loss of life (such as the Titanic) or circumstances of loss (Housatonic was the first vessel in history sunk by an enemy submarine).[12][13] Shipwrecks such as Mary Rose can also be important for archaeology because they can form a kind of accidental time capsule, preserving an assemblage of human artifacts at the moment in time when the ship was lost.[14][15]