The sea level was once 100m+ lower, rising to todays levels between 18000 and 5500BC. Recent evidence suggests the area in the North Sea, once landmass we now call Doggerland, was densely populated, possibly with cities.
If we wanted to do a large scale investigation, what would be the best method?
I have been envisaging the production of very large, bottomless concrete boxes that can be floated to the sites, have air released from inside so they drop to the floor.
I don't know whether water pumps will be needed to constantly pump water from the edges or if it is possible to seal the edges to allow the floor inside to be made reasonably dry.
The North Sea is notoriously rough, so the boxes need to be sturdy, possibly many dropped next to each other for support.
I don't know if the top of the box should be open above the sea level, or roofed below, under high air-pressure.
The boxes could have internal reinforced struts, ideally to allow them to be 1,000,000m3
Can anyone advise on the problems that could be faced, or if there is a better alternative?
EDIT: Another option I've imagined is a gigantic frame of metal pipes that could freeze the water immediately next to them, building ice-walls over a period of time. It is salt water and moving, so may not be possible at all. And ice floats, so the whole frame would need to be strongly secured to the seabed.
I'm actually limiting the realms of possibility to the 100m3. Originally, I was trying to devise a method to reclaim some area miles across. This could be Atlantis, after all.
EDIT2: @Molot has pointed out that the engineering idea I have been imagining already exists in some forms and is called a Caisson