Instructions
Speak with Coro in the forest path leading up to the Temple. He will give you a lantern for free. Pay 20 rupees to fill your lantern with oil and another 20 rupees to fill an empty bottle with oil, just in case.On your way to the Forest Temple, one of the monkeys will steal your lantern.
Enter the Forest Temple to find the monkey who took your lantern. Break the monkey free from the cage and he will give you back the lantern.
Enter the room that has cobwebs on the floor, covering a large hole. Equip the boomerang to knock two spiders in the room down to the ground, then slash them with your sword.
Pull out your lantern and stand on top of the cobwebs. Swing the lantern to set the cobwebs on fire and drop down into the hole.
Hit the cage with your sword to free the monkey inside.