Acatha Mystery Cavern?

[Hawkclaw]

In the Galafor/Acatha area, technically in Acatha, there's an odd little cavern North East of Gloamthicket blocked by a wall that seems to be an unmarked, unopenable Hidden Door.

My map indicates nothing within this cavern (Though I don't have Detect Hidden maxed out), and I can find no way to enter it. I even attempted every combination at the Fae Pools, with the urns, including the use of the Strange Green Stone. None of these worked, apparently.

I have been completely unable to find any information on this, at least none that provided any conclusive answers. Has anybody figured out this odd little cavern, or is it simply an unknown?