Hey all,
Unless I'm mistaken and missed a button, be careful with the enigma "Only the Fearless May Pass" in the Crystal Mines.
The puzzle itself is quite easy to solve, but requires you to throw an item on a pressure plate to open a door. Behind this door there's a simple wooden corridor. If you take the item off the plate and get into the corridor, the door closes behind you and you're stuck in the corridor. I haven't found a way to re-open the door from the other side and it's not like the corridor is too long, so I doubt I've missed something. So, whatever you do, don't save in this corridor or you'll erase your save and might have to reload from an older point.
-Nyast