how to get 「gurging tower key」in the area "gurgling gorge"?

[tsaiwilly3]

As title, I couldn't find the key so I could't unlock a tp site, even if I discover the upper area, I still can't find the key, anyone know the info?

[Jishwasher]

The key is in a different optional area that you can reach by going to the areas to the right of gurgling gorge. Specifically, it's in the graveyard area .