...holy crap.
...Wow. I finally found the main dungeon- who knew that it'd automatically open once you got close enough! Anyway, it was amazing. I especially appreciate the way there's no blackout between rooms. However, perhaps areas that you're not in at the moment or haven't visited should...
Eh, it's kind of tricky- you have to throw diagonally, which takes like ten times to work. Just try to get the boomerang controls down and it'll be a cinch.
See the torches to the upper left in the screenshot? There's a door there. Go through and down the stairs, to the right and over the orange tiles. See the rows of alternating tiles? Use the boomerang repeatedly on the switch to cross, then head to the left of the switch to right below the two...
That was a tough spot, too, but I figured it out. For one thing, first make sure that you have the ORANGE tiles down, and the blues up. You see the staircase on the north wall? Head up there and immediately to the right to the area with all the worm things and anti-fairies. Slaying all the wormy...