andrasz
If these are the conditions on the bottom (sea bed) are as described above, divers searching and finding an item such as the CVR component are pretty remote.
As a certificated advanced enriched air diver just disturbing a muddy,silty bottom with a hand or fin renders visibility to zero.
At 16 metres Nitrox 40 is a little OTT, Nitrox 32 is more than enough to give more bottom time and a quicker safety stop (decompression) on ascent.
Divers aiding suction dredging and filtering would be far more productive than literally groping around in zero visibility feeling for the CVR component.