Ok guys, I'll clear things up. From what I can remember during my own testing, the door *IS* able to be opened if you can manage to get into the walking animation underwater. Testing with a hacked metal cap is not good because you cannot open doors underwater with the cap on. You *can* get behind the door by BLJing like
this. However, it has no use as of yet. I have tried testing other weird strategies as well. Once, I can recall setting a warp to enter VCutM before the moat was drained (with Toad's Tool 64), collecting the red coin star, and then being shot out of the regular entry/exit point. Mario was standing underwater on the floor of the moat. Sadly, when the "celebration"/coin count animation ended and I chose "Save and Continue," Mario just shot to the surface of the water in his swimming animation. Basically, the only way this method would be possible is to somehow break the water physics enabling you to walk.
There is also one other theory, but I'm not sure how it would turn out. When you have a lot of BLJ speed while entering water, there is *one* frame where Mario is "walking" underwater. Theoretically if you could touch the door on this one frame, Mario may be able to grab it. The only way this could work is by using the slope on the right side of the castle to "walk" into the moat and touch the door.
