[kybernetikos]

If you can establish self-sustaining societies on the bottom of the ocean, you can be resilient to almost all of humanities great threats. It's technology that could also be used elsewhere in the solar system once it works well, opens up much more space for human habitation, and is also a much easier problem to solve.

[rbanffy]

Compared to deep ocean, space is easy. The rocketry is tricky, but you don't need to build foot-thick steel walls and, if something goes wrong, you can go outside.

Unless you are talking about bottom as in 10 metres down. That won't protect you in case something goes seriously wrong.

[vatotemking]

Good point. But the argument against it is that its still on planet earth. Still within the single point of failure that the parent mentioned.