Trope-a-Day: City on the Water

City on the Water: Several, even once we discount a few borderline cases like Landing, Phílae, which is really an Underwater City whose uppermost decks happen to stick out of the water.

Also on Phílae, most notably, are the several temporary floating cities likely to be present at any time, agglomerated together from a huge mass of houseboats and facboats and storeboats all lashed together into a giant city-like mass. (This is much more appropriate for Phílae than trying to build single large floating cities, since Phílae is a warm world without much land, and therefore remarkably prone to hypercanes. The ability to scatter and dodge them is very, very important.)

True artificial city-islands, on the other hand – of which the most famous is Calencine – were pioneered in Eliéra’s warm oceans as self-growing, self-repairing biotech constructs, with a customized biotech framework (including nutrient extraction and transport, and a bio-OTEC for power) supporting an island core of seacrete, island coral, and industrial bamboo.

But, in general, any world that has a hydrosphere and many that have an alkanosphere will have at least some of these.