You know how low lying islands are being submerged regularly because of global warming melting ice caps right, so we should build this super durable structure, preferably transparent, starting from the ocean floor and reaching all the way above sea level so it's as tall as the Eiffel Tower and then it should stretch out to either side to form a T. And a city should be built on top, one that is sustainable enough to never need complete refurbishment(?). And the building should obviously be strong enough to support the plateau city on top. It should heavily secured and unbreakable, anti-earthquake and anti-tsunami. It should be transparent so that people can take the elevator and go all the way down to the ocean floor and be able to see the ruins of civilisations past and ofcourse sea animal life. But not everyone should be allowed to do it, otherwise terrorists need only figure out how to destroy the building to bring the whole SeaT down.
Get it? SeaTs = Cities = Seats
Also since ^ is pretty flawed and won't work in real life, a more realistic SeaT would be to build one on good on land, and this actually would work in overpopulated cities. So there could be levels too. Like a Sea F or a huge Sea PI. And the richest people would be able to afford the highest levels and they'd have helipads there too where they can just fly around to different levels if need be, and so on.
SeaTs are the FUTURE!