Don't know how to open an unknown location (The Witcher 3: Wild Hunt)

As far as I remember, it's a cave with a Griffin inside, find the entrance along the mountains or on the other side. BTV it was shown in one of the early gameplay of the game

datebayoolo
The game can be completed without these unnecessary spaces.

datebayoolo
Spoiler

datebayoolo
In the story, with Keir.

In the story, with Keir Mets in the elven dungeon.Better to pass it early, because it gives the eye nihalani(removes the illusion) and can get into secret places.

GG4
It can pass, even without your advice plush.

datebayoolo
I also this place is not opened)

Thank you all!