I've all the hearts for 'Summit of the Sages' and can lend advice; several others have completed this as well and can help too (assuming they ever drop by).

[For organization's sake, let's start a thread that contains all answers to questions regarding each world (there's several threads below that have duplicate content). I'll start one for each world I've completed and can offer advice on.]

A Puzzle to Amaze
Observe the two statues at the end with the crests on their stomachs. They want the columns that are lined in up in front of them to match.

Rings
The last one isn't underwater; it's sideways above the water, at the far left end of the lake. You'll have to get out of the water and jump through it.