I can think of two nationally-significant archaeological sites in Central Europe - both were partially excavated about fifty years ago, to varying but fairly limited degrees, and then gently reburied, because there wasn't enough money to keep things going.
The site of one has a poorly-trafficked tourist centre today, the other is a clearing with nothing more than a tourist plaque. Both are likely candidates for previous capital cities, so they are obviously significant, but the money just isn't there to do anything about them. I seem to recall reading somewhere that over 90% of one of the sites remains unexcavated.
These are land sites, so relatively inexpensive compared to sea sites. If this is how willing we are to fund nationally-significant land digs, I imagine sea archaeology would be comparatively even more impossible to fund.
I think actually excavating stuff is beyond their purvue tho.
https://voyis.com/projects-endurance/
Endurance is 3000m down.
Search for the SS Central America: Mathematical Treasure Hunting, Lawrence D. Stone https://www.researchgate.net/publication/247823555_Search_fo...
1) have enough money to buy robots instead and get rid of the legal and logistic trouble
2) would want to use the dolphins for activities that grant a better return of the investment like marine engineering or war (mining/demining).
Every major of a coastal city in California, or South-Africa (with a big beach visited by thousands of swimmers a day), would pay solid money for bay-watching and shark deterrent services that really work without the need of eyesore nets. People love to swim with dolphins too so would be another tourism resource in itself.
The time of your dolphins would be just too valuable and expensive to do Archaeology.