Now that you have the Big Key you need to get to this temple's Big Chest. Go back to where the cracked squares are that you blew up to make the hole to get to the Big Key with. The floor fixed itself and you can now cross this path again. Go through the door above that. In here are some Hardhat Beetles. The puzzle in this room is that the arrows allow you to jump over a hole, but if there is no arrow on the other side you cannot jump back. Follow the arrows onto the large platform and defeat the Hardhat Beetles so they do not get in your way. You will need to throw a skull or use your Boomerang to activate the red/blue switch at the southern part of the room. Make the blue blocks go down. This part sucks. Throw a bomb onto the platform where the switch is. To do this place a bomb down then pick it up with A. Throw it quickly! You must be in between the blue blocks when it explodes and the explosion has to touch the red/blue switch. If it worked, you can now go left and open the locked door with one of your keys. Do NOT use the arrow to jump back down onto the big platform, yet. You should have 1 key now that you used one.
You have to get through this next part quickly. Lift a skull and throw it onto the Helmasaur who runs across the path to get to you. Get to the other side before the path falls down into the hole square by square. If the path fell and you cannot go north, exit the room, re-enter and try again. There's another Helmasaur at the end of the falling path so you might have to take two attempts and defeat one each time. When you get past this go use a key to unlock the door on the left. Now you're in a dark room. Watch out for Kodongos who shoot fire. There's no torches so this room isn't very fun. Go left, up, left, down, then left at the four way fork. Up, left, down, left, and up to get to a chest with Bombs. Go down, right, down, left, down, left, down, right, up, right, down, left, down, right to get to a chest with a Key. From there go left, up, right, up, right, up to get to a crack in the wall. Use a Bomb to open it, this takes you to the Big Chest, open it to get The Hammer!