I thought this was going to be more difficult than it was. After going to the stable by the Lost Woods and reading about the Korok Mask in the rumor book, I tromped around the woods but couldn’t find the hidden treasure chest. Then, after looking at the quest log description again, I had an idea 🙂
After a couple normal treasure chests, I came across this beauty.
To you non-adventurer, have at it!