Seasteading is a growing phenomenon that seeks to build an alternative society a float at sea. It can also have underwater features. I have seen many designs and the whole thing is so fascinating to me. Anything to counter the problems with the way human societies have historically been set up, allowing governments to run our lives. Now my understanding is that they will have governments, but you can still detach your section of a floating society to join another if you don't like the policies of the one you are currently with. I'm not sure how well that will hold up long term considering governments will usually find a way to be more intrusive as people empower and legitimize them, but it is an interesting concept nun the less and they will have cryptocurrencies. Here are some more designs and information about it.
