ACOUSTIC INSTRUMENTATION USED TO MEASURE DISTANCES UNDER WATER FOR SURFACE AND SUB-SURFACE NAVIGATION, NAMELY ACOUSTIC TRANSCEIVERS, UNDER-WATER TRANSDUCERS, A DIVER-HELD INSTRUMENT WHICH MEASURES THE DISTANCE AND DIRECTION OF A SUB-SEA TRANSPONDER, AN INSTRUMENT WHICH ACOUSTICALLY TRANSMITS DATA FROM A SUB-SEA OBJECT TO A SURFACE OR SUB-SURFACE RECEIVER, ACOUSTIC TRANSPONDERS AND ACOUSTIC RELEASES