I presume you're referring primarily to oil and gas. Are you aware of any systematic effort to search for other "stuff" on say, OUR continental shelves? Seems odd to me that various governments, NGO's and even individuals are willing to drop some fairly large bucks looking for everything EXCEPT signs of old civilizations just offshore. Most such finds have been accidental discoveries made by fishing trawlers and the like. There almost HAS to be more down there so why isn't somebody looking for it? Or if they are, why don't I know about it??? ;^)
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The knowledge of submerged ancient civilizations is extensive, but just not wide spread. It isn't something that the powers that be wish to disseminate.
There’s no economic return on such a search; and of course, even talking about using gov’t grants for scientists to conduct such searches can yield megatons of nasty comments. :’)
The whole article is quite amusing, btw, he complains about the billions spent on particle physics research, and that he doesn’t like boats. :’D