Just watched a documentary about the construction of the Three Gorges dam in China. Terribly sad to see all these ancient villages uprooted and cultures destroyed, but at the same time the frequent destruction from the unmitigated flooding of the river is too much to bear, and the dam pretty much had to be built.
In some cases, moderately-sized cities with multi-story buildings are now submerged by the water that has been impounded behind the dam. Assuming some of these are at a reasonable depth (<100 feet below the surface), will China allow recreational SCUBA divers to visit these sites? This seems like an interesting dive opportunity for visitors, and possibly a commercial opportunity for the locals.