Volke

Best answer as chosen by Asker / Ratings
Use the supercharge down into the little castle, head out the second door on the right, then jump when you get to the end of th platform. By this point you should be heading up the supercharge (in the wrong direction, obviously), which you should not worry about and keep going. Jump when you reach the end of the platform (stiull supercharging, or you won't make it) and glide around the building to eventually land on a hidden platform, which leads to another area of the castle.

In this ara of the castle, you will find the third dragon and the last remaining 127 gems (provided you collected the 373 that were obtainable outside of this area).