When you leave the Snow Temple, the blizzard has gone away. You can now make your way to the Tower of Spirits. Avoid the evil trains on the way.
By the way, you can now buy a bomb bag from Beedle's Air Shop. Just blow the train whistle when his air shop is close by and he will land. Then stop your train next to his shop to get in.
After buying something from him, he'll notice that you aren't a member of his club. Join the club and you can eventually get discounts and rewards. Check any postbox to receive your card.
Continue on to the Tower of Spirits. You will find a train platform here. Stop there to find the Bridge Worker's Home.
Bridge Worker's Home
Ferrus will be here. He will talk to you about warp gates. You might have already read about those in the note on Ferrus's wall.
Walk to the right past Ferrus to find four rocks in a circle. Play the Song of Discovery here to find a chest that contains 100 rupees.
Now go up the stairs, get any mail that might be waiting for you in the postbox, and go inside. If you choose the "Actually..." option, the Bridge Worker will tell you to go to him if you need a bridge to be built.
Go into and out of his house checking the postbox each time. I had several letters at this point. Then leave his place and go to the Tower of Spirits.
Tower of Spirits
When you reach Floor 8 of the Tower of Spirits, you find that it is very dark. You will need to use your boomerang on the torches to see the walls, then draw the walls onto your map.
Walk to the right to find a couple of unlit torches. Use your boomerang to light them.
The ghosts will leave you alone if you are in the light.
Next, go north and use the nearby bomb flower on the wall between the two torches to break it open. There is a treasure item in the chest.
Go to the southeast corner of the room and go up the stairs.
Collect the Tears of Light
Head west, lighting torches along the way. There is a sign here that says to blow out a torch in the corner of the room to see a faint light. Go to the northeast corner of the room, avoiding the Phantoms. If you use the whirlwind to blow out the torch in the northeast corner, you'll see a crack in the wall. Use a bomb on it (there is a bomb flower to the left if you don't have any bombs) to open a room that contains a Tear of Light.
Go back out and follow behind the Phantoms to make your way to the second Tear of Light. Then make your way to the left side of the room, avoiding ghosts by standing in the light, lighting torches, until you reach the third Tear of Light.
Go back over to the right side of the room and hit a Phantom in the back to take control.
Go to the southeast corner of the room and go back downstairs. Walk with Zelda over to the sign on the left that you couldn't read before to find out about the thin wall three spaces to the right. Use a bomb on it. There is a treasure inside. Go back upstairs.
Now go to the left. Use the Torch Phantom to walk across the dark maze to the left. At the fork in the path, go down, then have Zelda hit the two torches to open the door. Go up the stairs.
There are two switches in this area. There is one next to a door, and one to the right. Have Zelda stand on a switch, then have Link stand on the other. The door will open. Go through.
Read the sign just beyond the door, which says to illuminate everything to find the answer. In the middle of the room, you will find some tiles on the floor if you walk around with Zelda lighting the way. The tiles make a Z shape.
In the upper-left area of the room you will find a treasure chest with a random treasure item inside. In the bottom-right area, there is a red door. When you select it, you will have to draw a pattern. Draw the Z shape like you saw on the floor.
Since the Big Key is electrified, you'll have to have Zelda pick it up. However, when you do, a bunch of Key Masters will appear out of the ground. Make your way to the big lock, killing any Key Masters that get in your way. Even if you kill all of them, they reappear, so just have Zelda follow you while you kill the Key Masters in your way. Have Zelda throw the Big Key into the big lock. The Key Masters will go away when you unlock it.
With Zelda, go upstairs. A Mighty Zora Warrior will attack. Have Zelda hit it from the front, then have Link run around and hit it from behind. The Zora will jump away and then spit fireballs. Run behind Zelda to stay safe from the fireballs. Repeat this process until the Zora dies. Open the chest, which contains a random treasure item, then go through the door and up the stairs.
Tap the Ocean Rail Map to receive it. The step into the blue light to return to the train. Talk to Anjean to learn that Carben guards the Ocean Temple. She says to go through the Forest Realm to reach the Ocean Realm.