[jajko]

You want to find ancient marvels? Start digging literally anywhere in or around Rome. Or half of amazon jungle. Or around London. And so on. You can get much more 'value' in form of artifacts and knowledge from there for given money.

Submerged places... imagine how complex and slow archaeologic excavations look on the ground. Now move it 50m underwater in endless mud. Good luck looking for literal needle in the muddy haystack of 40,000km2. To find what... some fossilized wood or few arrow heads? That culture was very similar to ones on neighboring lands, no atlantis there.

One day, robots can scan and dig through there but there are so many better ways to spending money, any money, that it makes perfect sense nobody is doing it.

[fermisea]

It's a question of timelines. While I agree with Amazon, we know pretty well the periods in which Rome and London have been inhabited, but the question is more about understanding pre ice-age human settlements, of which we know nothing about because these are more likely submerged now.