Hi, I'm revisiting Oblivion and have rediscovered the doors in Frostcrag Spire I could never unlock. They are in the vault, down the stairs and through a door. One says "The Deepness" and the next says "Students Quarters" but they need a key to unlock. I've looked through the wikis and searched but cannot find anything. Does anyone know if these are unlockable and if so, how?

That's part of the Frostcrag Reborn mod. You'll find some hints on the mod's official site http://frostcragreborn.com/walk-through.html.

I think the student quarters key is in your bedroom. Once you get in there look on a self for the key to the deepness. You'll need a third key, but don't get that till you unlock the whole tower.

Ah thank you! I shall have a look around following that guide in the morning!