Going way past 100,000 meters.

Ayvalawn

I used the NODAMAGE and OXYGEN cheat and was able to use a Cyclops to go past 3000 meters where the terrain ends. It's very pitch black with a few bubbles, but I went so far I got past 100,000 meters and kept going. I'm pretty sure it's limitless now with the new updates, because before I was only able to go a tiny bit past 7000 meters and the game would crash.

Gr4phene

Now try to build a seabase there or use a terraformer and build it in the wall!

Racer1

Seabase integrity is based partially on depth. I imagine it would instantly implode at that depth -- unless nodamage affects the base as well.

Kouji_San

100Km... How deep is this friggin' ocean and for that matter dat planet size

Vandragorax

If you go far enough down, you eventually drop out of the sky and fall back to the surface