The ship is sinking. Survivors are fading fast, descending under the ocean's surface. All hope is gone.
But wait! What's that? A submarine? It's a miracle! Captain Nemo and his crew save the day!
Now the rescued travelers can go home. But where are they being taken? To an underwater city, where the inhabitants are dedicated to a peaceful civilization. Peaceful -- and secret. Once you're there, you can never leave. Quite a predicament for the survivors.
The 1969 science-fiction movie "Captain Nemo and the Underwater City" illustrated what life could be like living under the ocean if you had the time and resources to create such a metropolis. But why would you bother? (Other than developing a Utopian society, that is.) Did you know that a few people actually do live underwater? The settings are not as expansive as the Underwater City, the purposes are different and the timeframe is shorter, but dwellings do exist in marine habitats.
When you stop to speculate, there could be several motives for residing there, ranging from scientific to functional to aesthetic. Let's take a look at some of the reasons we might consider living undersea, progressing from fanciful to practical.