Any help finding the vault would be GREATLY appreciated! I've been everywhere I can spot in the castle except one side passage in the water as you SHOOT toward the labyrinth. I've tried to get to that passage, but the current is too strong and everyone starts drowning. PLEASE, oh PLEASE, where is the vault?!?! As specific as you can, please, as I know the castle like the back of my hand now. I need to get to the dungeon/vault to get the scroll and the relic. Thanks in advance.

Did you get the key from the lich ?

I'm having the SAME problem, and yes, I have the key the lich gave me. Where, oh WHERE, is the stupid door to the vaults? Zehnman, I feel your pain!

The vault entrance is back near the front door. Just head down to the area directly below the entrance hall and you will see a gate with a lock. You can't miss it.