See Barinade for the boss fight in Jabu-Jabu.
It is possible to megasidehop into the loading zone as an adult. This used to be extremely difficult, but new setups have been found that make it much easier.
This switch can be hit in a number of ways, including with the Hookshot as Adult Link. Of particular note you can use a bomb, bombchu, or even just the Kokiri Sword.
By performing a 35-pause slash extension with the Kokiri Sword you can extend the sword's hitbox such that it reaches up to the switch. Setup shown below.
This is the biggest sequence break for this dungeon. With it you can skip everything between getting the Boomerang and the last room before the boss. It skips killing the tentacles, Big Octo, and a few other rooms. There are two parts: getting over the gap in the room with the raising platform and getting through the door.
A well angled megaflip from the left ledge will make it
Recently, there has been increasing use of a megaflip using one of the boxes in the elevator room. It can be seen here.
A more difficult megaflip from a Biri can also make it over the gap. The area where you can start the megaflip from and still make it is small, and requires you to be as close to the ledge as possible. By luring the Biri, you can give yourself enough time to set up for a megaflip from it. Having ISG greatly helps position yourself near the ledge.
Using the Biri, you can hover up to the ledge after the miniboss, and then lower the platform like normal.
This video goes over four setups for the trick. The final A press to open the door is frame perfect for all setups.
Original video (slower setup)
The first method found. You need a bottle with a bug or fish to do this trick. Using ocarina items allows you to keep the item in the bottle.
Ocarina items method:
Bottle switch trick:
This was the second method found, and significantly harder than the bottle switch trick. However, it can be done without a bottle, so it was used commonly until Method 1 was discovered.
Original video - For this method, pull out the boomerang and aim as high as possible, and just a little left of the web. As soon as you release it, start sidehopping and when it starts coming back it should hit the switch.
Line up against the wall beneath the switch and pull out a bombchu. Release it on the 5th flash and it should activate the switch.
[Video needed]
You can also use jelly hovering to reach Big Octo's room without killing the tentacles. He can be defeated with just a weapon, but a deku nut makes him much easier.
For getting behind Big Octo, the idea is to place Link somewhat behind that front left corner of the central platform. The cutscene of the boss spawning attempts to move him. Moving upleft after throwing Ruto just aligns the camera so that it is fast and easy to line up your backwalk and backflip to reach the correct spot.
For glitchless AMQ, the ideal place to store deku stick jumpslash damage is in the final tentacle room with the four biris. After killing everything, move towards the door and jumpslash at the last moment before the door opening cutscene takes over.
If you aim to jump at the left corner of the switch, then press down for 1 frame right as the jump begins, you'll get it. Other frame combos work too, but its very finicky, and you can easily lose time to missing the switch.
These methods of entering Barinade's room are commonly referred to as "boss key skips" even though the child dungeons don't have boss keys.
This HESS begins in the elevator room and clips into the pre-boss room to reach the boss load zone. See instructions in video. As shown in the second video, the switch from ESS left to ESS right requires less timing precision if you switch to ESS down instead.