I am stuck here too because I keep trying to get the water level to go up, which it does (there's a clink that lets you know you're done, I surmised), and then when I try to swim up the water level comes crashing right back down again. How do you keep it up there, or are you supposed to?
Roll until the gear has momentum, then stop rolling. If you keep rolling all the way until the end, the gear will roll again and bring the water back down.
Spoiler: Or down to the right level to move the blue jewel to the left? I haven't been playing for awhile because I can't seem to get to the right place to move the jewel.
Te sun jewel starts out at the utter right, (when you first encounter it) and you need to bring it to the utter left, the room where it needs to go is connected to the rest of the temple only via
one up-down tunnel. There are sun rays shining through a hole in the stone ceiling.
To get it there,
move the veil up,
move the jewel to the left of the room,
move the veil down,
move the jewel to the left of the lower chamber, below the path that leads to an other upper chamber,
move the veil up,
move the jewel to the left, over a path that leads to the same room as the gear that controls the veil.
move the veil down, now the jewel is close to the control gear,
move the jewel to the utter left, inside the side path,
move the veil up, now the jewel is in the charge-up room.
move the jewel to the left, below the sun rays, then let go, and the jewel should fall out.
Now bind the jewel and swim down to the dark path, while the veil is in the high position. You only need the jewel to see in the dark, once you've opened the locked song-door, and moved to the left side of the temple and up, you no longer need it. After you've gained the sun form, you no longer need it at all.
Also can't get up the chimney to the right of the veil in search of rukh eggs; she just falls back down the second she touches the wall. Or, I'm just really bad at this wall-jumping thing, even using the space bar with my left hand and the mouse in my right. Using beast form. Getting tired of swimming around and killing things, and I could open an underwater restaurant with all the recipes I have; eight arcane poultices and two special bulbs to make more, for example.
This is a tricky thing to do, you need to jump away from the wall, into the opposite wall, before Najia lets go of the wall on her own. So you have to quickly move your mouse to the left, click, then quickly move the mouse to the right, click, etc. For your convenience, there is a break halfway, and the second part chimney is a bit easier, with a couple of slopes.
If you think this is hard, then getting the memory at the top of the sun temple is going to be a murder, imagine a chimney consisting of two perfectly straight up walls, and is a lot wider. I know it was difficult for me to get there, and still is, despite having been there several times already.
