Water Temple Boss Key skip Edit
Discovered by MrGrunz
To do this you need to Bomb Hover until the top Link's head is aligned with the top of the Boss Door's frame. Then change the camera angle so that you face the wall, and simply Sidehop-Jumpslash to go through the door and hit the trigger to enter the Boss Room.
How to do Edit
Activate the Infinite Sword Glitch which can be done off of the Boss Key door if you don't have Bombs with you. Pick one of the walls adjacent to the Boss Key Door, and Staircase Hover into it. After hovering as high as you need to get, you must change your angle. Drop a Bombchu (it should ride the wall), and Z-Target it. Now try to move backwards like you're trying to backwalk. Let go of joystick then roll directly afterwards. When the roll is nearly finished, tilt the joystick to face the Boss Door. Sidehop-Jumpslash through the door.
It can also be done with bombchus, as shown below:
Get to the Boss Door as a child Edit
Discovered by MrGrunz
As a child, you can't use the hover boots to Hover Boost over to the door before the Boss Door Room. Instead you must hover over there. Now you have three options: Either Bombchu Hover using the slingshot, Megaflip off of a Tektile, or use a Tektile to hover halfway and Bombchu Hover across.
Open doors without being on solid ground Edit
Discovered by Pokey
You can get into the Doors on the second and third floor of the Water Temple without raising the water level. Just set a bomb down, wait for explosion, pause, and equip the Hover Boots. The recoil from the blast will allow you to run at your max speed instantly, and reach places that are farther away. Now unpause, quickly turn around and open the door.
Small Key RBA Edit
Discovered by kazooie
Beat Dodongo's Cavern without getting the bomb bag. Before you pull the Master Sword, go Bombchu Bowling and win the Big Bomb Bag. Now go back to Dodongo's Cavern as adult and obtain the Bomb Bag. This will put a Bomb Bag over your Bombchu slot.
Now go to the Water Temple with a Bottle on B and the Bomb Bag you now have on C-Right. Now if you empty or put an item in the B Bottle, you'll receive a number of Water Temple Small Keys equal to the hex value of your B Bottle. See Reverse Bottle Adventure for more information.