So why doesn't Shadowrun have something whacko like that? I could see a at least one or more corporations turning to underwater living to better gather resources, ectra rather then head to Mars. 
There are multiple Arkoblocks, aquacologies and other marine-habitations. That said, they're hard to maintain, not always worth the value, and there aren't any dragons on Mars (that we know of). The Sea Dragon can get pretty territorial.
20 Arkoblocks, each capable of having a population of up to 3 million each. They are the largest marine population centers, built from the ocean floor to tower over the waves.
An unidentified number of aquacologies, completely underwater and/or submergable, the largest has 8 thousand people in it, with one of the contender for largest having 3 thousand.
An unidentified number of aquacities, with less than 1 hundred people in each.
There's also a dozen Red Wheel Max-Sec Prisons, each able to hold around 5 thousand people. They're basically giant ships that sit as low in the water as possible with a ruthenium coating to conceal their whereabouts.
If you want more information, read Hazard Pay, from 4th Edition.
