What is your approach for constructing a city above or beneath the water?

[Patrism]

Constructing residences above or below water can potentially alleviate the housing crisis, and if I don't initiate this project, someone else may do so in the next three decades.

However, if I have only the idea and lack expertise, where should I begin? I am considering pursuing an engineering education and experimenting with constructing a houseboat.

Is this approach flawed? What other steps should I consider taking?