I also loved this idea! I don't think it's feasible but sometimes an impractical idea inspires another idea that is workable.
The time-on-station and the materials needed to drain and then thoroughly search the lagoon would be prohibitively expensive, in my uninformed opinion. We can reconsider when we locate a few multi-million dollar donors.
But, as Marty said, cofferdams around small areas should be doable. (Since I know nothing about civil engineering, I don't see any problem with it.)
This is probably all fantasy, but since we haven't had a lot to talk about lately I'm going play with the idea.
Let's flesh this out. What materials do we need to build a cofferdam 20 feet high? We have to transport it to Niku, so what does this weigh and how much space does it take up? Where do we get the materials? Can we purchase them "locally" in Fiji, or Hawaii, or will they need to be sent over from CONUS?
After writing that last paragraph I spent ten seconds with Google and found
this. You know, this might not be so crazy.
Scott had an idea about draining the entire lagoon with an Archimaedean screw, but I'm thinking of ordinary pumps to drain the water inside the cofferdam. Pumps are powered by electricity, which means we need generators, so we need gasoline. I reviewed the
specifications for Nai'a and I don't think the operators envisioned using her as a tanker, so we'll probably want to store several dozen 5-gallon gas cans in one of the staterooms, and we'll just have people carry them across the reef and a mile or so up the beach to wherever we're working.
Or we could just use a siphon and a bunch of buckets.
How do we identify the promising areas that we want to inspect?
How large an area can we dam off, and how long will it take to drain an area?
Once an area is drained, what kind of surface do we have? Would it be solid? Soft mud? Quicksand? I've heard Ric has stories about quicksand.
Do we need to follow archaeological protocols to explore the exposed surface? Or just grab shovels and go for it?
There are lots of other questions, but I'll stop here. This could be done -- that is, it's physically possible. Feasibility is another issue, and we have to get approval, but as I said, I'm considering this a fantasy. How does that quote go -- "I have abandoned my search for truth, and am now looking for a good fantasy".