Gregory's ServerThe first two lines of the Wikipedia article on cavitation:
Cavitation in fluid mechanics and engineering normally refers to the phenomenon in which the static pressure of a liquid reduces to below the liquid's vapour pressure, leading to the formation of small vapor-filled cavities in the liquid.
When subjected to higher pressure, these cavities, called "bubbles" or "voids", collapse and can generate shock waves that may damage machinery.
@MarvClowder @deliverator @clive and now.realize.that the strongest sonars can make water boil around them on full blast and that a lethal noise level is possible for literal miles...
And whilst friendly submarines should.cease using sonar whilst divers are out, SEALs usually don't tend to be get deployed in friendly waters... ^