Spend 10 Rupees to enter the Training Ground. It's the gated door in the SE of your map.
There are two treasure chests in the entrance, in them you will find ARROWS and BOMBCHUS.
Use Din's Fire to light the two torches. This raises the bars on the left lion door. Enter.
In this room you have 1 minute to defeat the Iron Knuckle. When you do so, you'll get a treasure chest with a rupee in it and the bars will raise to the next room. Go through.
Here you must gather all of the jewels (aka Silver Rupees) in 1:30. Use your Longshot to get to high ones, slash through icicles to find hidden ones, kill the Freezzard, and make sure the one by the "pit" is the last one you get. If you get it earlier, it will
you'll have to start the whole process over. Once you get them all, the bars on the door across the way will be lifted. Use your Longshot to pass through the flames and get through the door.
In this room you have one minute to kill all of the enemies in the room. Once you do this, the bars on the door will be raised an you'll get some ARROWS in a treasure chest.
Notice how Navi's trying to tell you something. Use your LENS OF TRUTH to see the hole in the wall. Stand back from it and play the Song of Time to make a block so you can reach it. Climb up and you'll see it's iced over. There's BLUE FIRE in the room below. Collect some and release it on the ice. You'll see a door. Nice. Go through it.
You're now in a room with lava below. Longshot to the top of the structure and look down. Locate the switch below to raise the bars on the door.
Get down to the rotating main level and shoot the four eyes of the statue. This will drop a treasure chest with a BOMBCHU in it.
Go through the newly opened door. Here you will, once again, have one minute to kill all of the enemies in the room. When you do this the bars on the doors will be lifted and you'll get some ARROWS in a treasure chest.
Note the switch above the door. Hit it with an arrow, then step on the switch in the room. This will get you to a treasure chest with a SMALL KEY inside.
Exit out the door with the switch above it. Hit the rusty switch with your hammer. This will provide you with a Longshot point. Take it.
From this point, locate the unlit torch next to the barred door. Hit it with a FIRE ARROW and the flames on the platforms will temporarily go down. Now you need to collect all of the Silver Rupees in the room. Remember your HOVER BOOTS.
Once you collect them all, the bars on the door next to the torch will open. Go through it.
Now you're told to collect the underwater gems. Burn the webbing, then kill the big jellyfish. Put on your ZORA TUNIC and IRON BOOTS and jump in. Look out for the enemies and either swim around or use the LONGSHOT points along the wall to get to the Silver Rupees.
Collecting all of the Silver Rupees will give you a treasure chest with a SMALL KEY inside. Swim up to get it. Exit out of the room and go back into the lava room.
Here, Longshot to the lit torch across the way, climb the stairs and go through the door.
In this room you have one minute to defeat the bad guys. In the treasure chest is a SMALL KEY.
Go back to the lava/fire/hookshot point room and go through the hall behind the upper hookshot point.
Go through the door on your left and through the next door. You'll be at the main entrance.
Go through the center door. Work your way around the various cages/pathways until you can hit the switch in
the middle with a hammer. This will reveal a treasure chest. But, in order to get to it, you have to
go back to the room with the statue with the 4 eyes that you got to through the left door in the main entrance area.
Work your way around until you get there...you're going to have to call the block with the Song of Time to get there.
Stay on the second floor and go through the door there. This is where the treasure chest is. You'll
get the ICE ARROWS.
Exit the Training Ground.