A typical bottom mine consists of an explosive case and a firing mechanism. More complicated mines may be outfitted with a variety of other features. Air-delivered mines may be fitted with a parachute and tail fins to lessen the impact as it strikes the water. A typical moored mine uses an anchor, which is located on the front of the mine. Upon impact with the bottom of the water, the anc hor section breaks away and the rest of the mine rises upwards on a tether cable until it reaches its pre-determined depth.
Magnetic mines utilize a magnetic search coil or magnetometer to detect passing ships.
The older, heavier search coils are used in bottom mines to detect changes in the earth's magnetic field caused by passing vessels. Newer magnetometers are often used in moored mines and can detect ships or submarines in any direction. Acoustic mines employ a hydrophone to detect the sounds emanated by ships and submarines including engine and propeller noises. Such sounds must meet certain criteria, including frequency band and must increase in volume at a prescribed rate or the mine will ignore them. Pressure mines use electro-hydraulic pressure sensors to detect ships or submarines.