Where is that enemy U-Boat?

[Seb <sebastian.hunt@virgin.net>]

How does one express relative positions in the 3d space beneath the surface of the water? Do the military use an absolute or relative x,y,z system, or do they refer to an object as being 'off the starboard quarter and down a bit'? Perhaps they say 'Starboard, 4 O'clock!' 

Maybe they just point and shout 'Over there, Captain!'.

I'm sure all of these work, but is there a standard method?

Seb Hunt (an Aquarian)
England

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