US Officials say that Iran has laid at least a dozen sea mines in the Strait of Hormuz of at least 2 types. Maham 3 - tethered mine for use in water up to 100m - floats just below the surface attached to a sinker on seabed. 300kg warhead Maham 7 - bottom influence mine. Laid on the seabed in shallower waters. 150 kg warhead. Both are triggered with either acoustic or magnetic fuses. Mine warfare personnel are routinely trained to deal with these types of threats.