Inside Jabu Jabu's Belly

First room without slingshot or explosives

Deku Stick Super Stab

You can use a deku stick super stab to hit the switch in the first room.

Slash Extension

You can also use slash extension to hit the switch.

Big Octo Skip

Megaflip

You can use a megaflip to skip the Big Octo fight, making Ruto useless after getting the Boomerang. You can then use a cutscene item (Zelda's Letter, beans, bottled item) on the first frame you land on the blue switch to keep the door open.

Damage Boost

With a precise damage boost combined with a jumpslash, it is possible to skip the big octo. This method is considered glitchless. In order to also skip the blue switch glitchless, it is necessary to do a roll from a very specific spot on the switch and open the door on the right frame.

Slimy Skips

By dying while moving through a slimy tentacle, you do not receive knock-back which lets you pass through the slimy thing if revived by a fairy. If you do not pass through it quickly, you will take damage without invulnerability frames until you die once again.