A naval mine is a self-contained explosive weapon, planted underwater and left to wait, that detonates when a ship touches it or comes within range of its influence sensors. Sea mines are Navy weapons, distinct from Army land mines — laid by surface minelayers, submarines, or aircraft, and left in place from hours to months to defend friendly waters, blockade an enemy coastline, or destroy shipping in a strait or harbor approach.
How do naval mines work? Every mine has a case holding the explosive filler, a firing mechanism, and (for moored mines) an anchor. Mines are grouped in two broad classes: independent mines, which fire automatically once armed, and controlled mines, wired to a shore station that can observe or trigger them on command. Independent mines fire by contact (a ship physically strikes a horn, antenna, or the case itself) or by influence — detecting a passing ship's magnetic field, propeller and machinery noise, or the pressure wave it pushes through the water, with no contact required at all.
- Broad classes
- Independent (self-firing) · Controlled (shore-station fired)
- Position in water
- Bottom (ground) · Moored · Drifting
- Contact firing
- Electrochemical horn · Galvanic (copper/steel sea battery) · Mechanical
- Influence firing
- Magnetic · Acoustic · Pressure
- Laid by
- Surface minelayers · Submarines · Aircraft (parachute or free-fall)
- Countered by
- Degaussing & deperming · Mine hunting · Minesweeping (paravanes, noisemakers, magnetic tow cables)
Everything below is drawn from original Bureau of Ordnance publications in this archive — the same manuals issued to the mine warfare and gunnery personnel who handled these weapons.
- Naval Mines — Types, Components & Firing Mechanisms (Ch. 13A) — classification, mine cases and anchors, accessories (clock delays, sterilizers, ship counters), and contact/magnetic/acoustic/pressure firing mechanisms in full
- Aircraft-Laid Naval Mines (Ch. 13B) — minelaying by aircraft, the Mark 10 Mod 9 moored mine, parachute assemblies, release mechanisms, and arming wires
- Naval Mine Warfare — Strategy, Tactics & Countermeasures (Ch. 13C) — defensive vs. offensive fields, strategic vs. tactical mining, command problems, and the three major countermeasures: ship treatment (degaussing, deperming), mine hunting, and minesweeping
- OP-898 — Naval Mine Identification Manual (1943) — the Bureau of Ordnance's official illustrated reference, with outline drawings and dimensions for all 67 mine types in general use
- OP 1507 — Japanese Underwater Ordnance: Mines, Depth Charges & Torpedoes — U.S. Navy intelligence summary of Japanese mines with identification data and handling precautions
- OP-831 — Depth Charge Projector Mark 6 — the shipboard weapon used against submarines, a close cousin of mine warfare
- Coastal & Riverine Craft Armament — includes the River Minesweeper (MSR) and Coastal Minesweeper (MSC) classes
- ▶ Littoral Combat Ships (LCS) — the modern Navy's mine countermeasures mission module