What are the torches Inside Zora's Domain used for?

Question

In Zora's Domain there are a number of torches which go out after some time, 2 are behind the Waterfall and one is in the shallows by the shop. I've tried lighting them all and i think i do get them but they always seem to still go out, i remember in some dungeons these kind of torches will go out if the puzzle isn't cleared in time.

I am wondering what these torches are for.

Answer 1

If you light all the torches a chest will appear behind the waterfall, which will contain a Piece of Heart.