HMS Echo
Little off topic but let us not get carried away with the capabilities of HMS Echo....
I spent 3 years on board and her sister ship as a civilian contractor providing support for the survey equipment and teaching Navy operators how to use it - (yes as a civilian - really!).
The vessel is fitted with survey equipment for up to 1000m depth. It is great at finding wrecks. A sidescan sonar can only see a 200m wide swathe and you can only survey at 4.5knots. Her hull mounted multibeam will see a much larger swathe, but it is not designed for detecting objects - just changes in seabed. The 'hit' rate per metre squared is too low.
While Echo is a valuable asset, but it is not magic and is limited by the equipment. What may be of more use is her ability to act as a command platform.
I now work as a Survey Party Chief running geophysical surveys (as well as a flight instructor) - so I do know this industry as well as flight instruction.