>they wont let us colonize antartica.
>they wont give us ANY land of a already existing nation.
>mars will take too long.
we need to literally become liquid breathing Atlanteans.

Regular saline at 8 bars of pressure has a oxygen saturation limit high enough that mammals can breathe it if saturated https://apps.dtic.mil/dtic/tr/fulltext/u2/671793.pdf
Mice Survived 4 hours breathing nothing but saline and only died due to co2 build up in the blood. With some very minimal metabolic modifications to make humans resistant to co2 build up humans could live indefinitely breathing saline ( it would be harder breathing but adaptable). This means we can start colonizing the 75% of the planet covered in water by building bubble pockets of partially desalinated water under the ocean at depths 80 meters and under. eating, shitting and sleeping could occur in air pressurised habs for comfort and cleanliness. but we would work and play outside breathing water.

We literally wuz atlanteans, and we will be again...