What really lies beneath Antarctica? Why are so many things hidden?

I came across this video recently that dives into what might be under Antarctica’s ice—massive cave systems, heat sources, even signs of forgotten civilizations. Sounds crazy, but the way it's presented really made me think twice. 🤯

It’s the second part of something called Secrets of the Deep, and it doesn't push wild claims but asks some very compelling questions about what's being kept from us.

Watch it here if you’re curious:
➡️ https://www.youtube.com/watch?v=PmvkU4ihAt4

But here’s what’s bugging me:
Why is access to large parts of Antarctica so restricted? Why did so many nations agree on the Antarctic Treaty to keep it untouched? Is it just science… or is something far older buried down there?

Anyone here ever looked deeper into this?