banging cover, I was hoping for a bit more in the room descriptions and some of it left a bit too much the gm to fill in I think. Adding a random encounter table and pinning down some of the rooms would be better i think.
Rather than leaving it as 'perhaps a bobcat or small bear', making it a specific creature that has this specific reason for being there and fits the theme. Similarly the Jotunn sounds amazing, but I was left wondering what their name is and why they're there.
Cool well of secrets concept though for sure, I could see this being a useful location to have hinted at on a rumours table.