It is you! The ones who came to the village not too long ago. I knew you would conquer the the water temple! 
I just knew it! Sorry for coming in here on short notice, but I thought I would come to help you! 
But as I came into the temple. there was a secret passage leading straight to the lever! 
I then thought I would wait here to see the ones who defeated the guardian was still present. 
And here you are! Oh, and I almost forgot. Theres a temple within the mountian's of the northeastern region.
(Where there isn't any tree's...) Its hard to locate on the map, but its not too hard to find.
It goes underground too, so be extra careful where you tread. 
I'm afried thats all the help I can give you. Please do your best to restore peace to the world.