They called it a moat. In just the same way, the planners of Sea City knew that their wall of concrete would soon be brought down if the great waves were not checked before they crashed up against it. So they built a 20th-century version of the medieval moat. These are positioned at some distance from the wall, and being part-filled with fresh water float low in the sea. They are enough to break the back of the giant waves coming crashing in, reducing them to harmless ripples by the time they reach the wall.
Sea City is a possibility all right.
It could be started tomorrow if the money were readily available. Perhaps, during your lifetime, you will have the choice to live on the land-or to live on the sea. All credit goes to the excellent TV Century 21 organisation which published TV21 Magazine and Annuals in the 1960s and early 1970s. A future community based in the Ocean is still an exciting possibility. See the work of the Oceania Community and some of their beautiful images or the New Utopia Project for details of current work.