Getting large swaths of the seabed is going to be beyond the resources of almost everyone. They spent like $200m hunting for MH370... and didn't find it. And on the scale of the ocean that was not a large swath by any means.
Ancient human tools have been found by fishing boats in Doggerland, the portion of the North Sea that used to be a land bridge between Europe and England. I bet there's a whole lot more discoveries to made just a few miles offshore.
I would imagine at some point getting overhead satellite imagery by plane of the entire world seemed impossible - as did street view coverage of the entire US - but not the craziest expense once you have the ability to do it once.
I think this is one of the systems used during the MH370 search, apparently it can scan 192km² per day.
There are 161,000,000 km² of ocean, so you'd need at least a million days or 3,000 years to scan the whole thing, give or take.
I would think they would need a version that doesn't need the ship nearby to scale - but would still guess this is something that will be accomplished on the order of 30 years from now.
Sorry if you aren't the best choice, but I had to ask someone in the thread.
Why? I mean why all the ocean?
If the purpose is to find archeological sites, most will be on the continental platform.
Certainly doesn't sound easy, but it'd be interesting to hear from anyone who works in this area.