Yeah!

It's true that It won't be Hidden for a very long time and people will eventually discover them.
I was thinking, what If there are multiple entrances that will lead to "different parts" of the hidden dungeon that could not be accessed through the other part of the hidden dungeon?
I.E. (The Entrances should not be far apart and should be in one Area)
-You find Hidden Dungeon Z.
-You go through entrance A. You end up in a Dead-end, with a locked Door.
-You exit the Dungeon and search for another Entrance. You find entrance B. You fight
Key-holders. you obtain a Key.
-You find an old lever that won't budge. You go to Entrance A. You use the key and the
Locked door is now open.
and so on...