magnetic mine

mine that is set to explode when it senses a change in the magnetic field

A naval mine is a self-contained explosive device placed in water to destroy ships or submarines. Unlike depth charges, they are deposited and left to wait until they are triggered by the approach of or a contact with an enemy ship. Naval mines can be used offensively, to hamper enemy ships or lock them into a harbour; or defensively, to protect friendly ships and create "safe" zones.
See more at Wikipedia.org...

Noun
1. (nautical) a marine mine that is detonated by a mechanism that responds to magnetic material (as the steel hull of a ship)
(hypernym) floating mine, marine mine
(classification) ship

A mine which responds to the magnetic field of a target. Also called "magnetic circuit". See also mine. 1/12/76

Mine dont la mise de feu réagit au champ magnétique provoqué par un objectif. Aussi appelé "mise de feu magnétique". Voir aussi mine. 1/11/75

Voir mine magnétique. 1/11/75

n. ทุ่นระเบิด