This vast glacier cave was a space where the heat from near the mantle was released through cracks in the surface and yet could not penetrate the thick land above, only managing to melt the ice layer closest to it. Once the heat dissipated, the area became a sprawling, empty cave spanning nearly several kilometers.
This was also the gathering place for all dangerous S-level containment items.
In the Polar Research Area, every item had an indisputable reason for not being released, whether because it was dangerous or because it would make other things dangerous. In short, the cave could be considered a convergence point for countless ways to destroy the world.
However, the containment measures here were exceptionally simple—they just needed to... be left alone.
