I have 1st 2 tablets. I'm in the area where I put 2 gems in sockets and pushed 2 levers which opened a door to swim down by a mermaid who says she's trying to win a prize by finding the tablets. Anyway, I've combed this whole area thoroughly and have found nothing other than 3 obvious chests which didn't have the tablet. Is the 3rd tablet in this area? Help, thanks.

Sounds like you were close but swam down instead of looking up - is this the fat "Y" shaped room?? where there are locked doors which once opened (did you keep the doors open?? BOTH??) you flip the switches?? If yes - when you go back to the middle of the Y shaped room an alcove opens at the bottom of the "v" that makes up the upper part of the "Y" (are you totally confused??) The 3rd tablet piece is in the alcove.

There is an opening there where you can swim down, but that isn't what you want to do here.

Wyv

Really hope I didn't confuse you too badly!