Underwater Civilizations Take 3

Please follow the rules regarding this subject. It’s not worth starting a conversation about such a controversial topic unless you fulfill the full, college-paper requirement imposed by hhyyrylainen, as it will just cause arguments

Also, melting metal was solved here: The Holy Grail: Hhyyrylainen’s Challenge of UC Metalworking Completed and Formalized with 47 Citations! . The current issue is shaping said metals and onward