EDIT: SOLVED

I entered with the mirror shard, flask of rubbing alcohol and the fire-breathing baton.

I lit the fire with the mirror, but I wasn't able to enter the water. I saved and loaded and then I was able to enter the water - except I was walking on top, not wading through it, and there were no confrontations with tentacles.

I reached the end with the squid-freak, and there's nothing I can do. When I try and use the baton to breathe fire, all Sarah says is "I can't do that" and variations. Saving and loading from there didn't help.

I have saved games from before entering the cave, but every single time I try to use those, after I enter the cave I can't enter the water at all no matter what. Not after the fire is lit, nothing. Only the one saved game I made earlier works to even let me enter the water.

I would like a saved game from just after the squid is defeated, please. (preferably in slot 7-12)

EDIT: Solved because I am dumb. It was obviously a bug that I could walk on the water. It wasn't until I loaded a much earlier saved game and had Inferno teach me how to blow fire that I realized what I was doing wrong. I wasn't lighting the baton in the fire. That worked.