The Legend of Zelda: Ocarina of Time Master Quest/Inside the Deku Tree

Ascend to the second and third floor
Walk into the first room. Turn to the left, there should be a ladder (do not use the vines, there's a skultulla crawling on them). Jump across the log (be wary of the keese) and in front of you there should be a large chest and a gohma egg. dispatch the egg before it hatches (or kill the larvae with two sword strikes) and open the chest

you now have a map of the dungeon.

Adjacent to the chest is an oddly placed crate, roll into it and you will find your first skulltula. Since the only door on this floor is locked, the only way to go is up. Climb the vines to the third floor.