I thought your first post was funny. No appology needed.
I checked out the site before my post and I still had to ask.
So why sink a container and flood it with water? To spin a turbine
with the high pressure water pouring in....trouble is, how to get that
sunken wreck back up without using more energy than you produce???

Inmpossible, yeah? Boyle's Law and all the heat loss during the
pressurizing Mumbo Jumbo