I am in Crystal Temple, in the area where there is a magic head with lots of candles to light from a moving platform and where there are two large, rotating platforms. I managed to operate all of these, and I noticed that there is some shallow water underneath the second rotating platform (I can walk around in the water). I didn't know where to go from there, so I checked Sephirosuy's walkthrough.

He mentions an underwater switch that I need to press for a boulder to come down (probably to block the underwater hole which feeds a nearby waterfall). I looked all over the place, but I don't see any switch.

Anybody knows where the switch is?

Why don't you ask the person you got the walkthrough from. I'm at the same part and i don't know where the switch is either.

u need to throw a magicite crystal at the switch just under where the platform is as you can't target it with the magic ring

wat can you elaberate plz and thank you

not to be a killjoy or anything, but there aren't any treasures in that room, and it's so much easier if you just go back to the save crystal and take the other path. This leads to the same destination without all the stupid puzzle which just wastes magicite.

The only "downside" I can think of is that when you kill all the bats in the "castle wall" room, it's fairly hard to get to the SE door without getting zapped by the bat duo down there.