With bombchus, obtained from getting 40 skulltulas.
You actually only need one chu to do it, and that's to blow up the rock at the entrance. If you use the hammer to get Din's Fire and Magic, you can use that to knock down the stairs to 2fl and every other bombable wall in there falls to the hammer.
A warning though: If you skip the bracelet and then become an adult but forget the scarecrow song, then getting to the fishing pond becomes much harder. And if you TSC'd past king zora as a child, then you need to poe hover in order to get boots to steal the rod.
I wanna know what Nook is talking about.