While mines threaten only those who choose to traverse waters that may be mined, the possibility of activating a mine is a powerful disincentive to shipping. Īlthough international law requires signatory nations to declare mined areas, precise locations remain secret and non-complying individuals may not disclose minelaying. Mines allow the minelaying force commander to concentrate warships or defensive assets in mine-free areas giving the adversary three choices: undertake an expensive and time-consuming minesweeping effort, accept the casualties of challenging the minefield, or use the unmined waters where the greatest concentration of enemy firepower will be encountered.
Naval mines can be used offensively, to hamper enemy shipping movements or lock vessels into a harbour or defensively, to protect friendly vessels and create 'safe' zones. Unlike depth charges, mines are deposited and left to wait until they are triggered by the approach of, or contact with, any vessel. A naval mine is a self-contained explosive device placed in water to damage or destroy surface ships or submarines.
