The best thing to do in the beginning is to immediately enter the door on the left. Taking the path with the suspended boxes in fact, you will not go very far.
There is a bonus area here, to access it, consult the relevant page. Stomp the two crates in front of you to get some crystals. Then jump on the rafts that move suspended over the void. By jumping from one raft to another, you will have to reach a block of ice on which there is a golden key. If the flying Dantines are bothering you, you can take them out with a flick of the tail. After taking the key, go back to the previous area.
Now you can start breaking the long line of suspended boxes. Start from the last one, as usual, jumping from one to the other, because if you break the first ones first, then you will no longer be able to reach the next ones. In the last box, however, there is the first Gobbo, while all the others contain crystals. Be careful because just beyond there is a Dark Dantini that will try to hit you if you get close. After destroying all the crates, kill the Dark Dantini and cross the pool of freezing water on the right, jumping on the small platforms. On the other side you will find a small stack of crates. Below them is the second Gobbo. In the chest in front you will find the red crystal and in the others some clear crystals. Then open the door on the left with the golden key and enter.
Here you will have to go through the minigame you saw in level 1-3 again. The only difference is that here you will have to make disappear penguins that come out of the pools instead of sheep. If you manage to pop enough of them, you'll get the third Gobbo, otherwise extra lives.
Then go back and go all the way back until you reach the area with the rafts again. This time, go up the row of rafts until you reach the next door. In front you will find two crates. One of them contains the green crystal and the other some clear crystals. Then enter the door.
Hoist yourself onto the rotating platforms above the freezing pool. Climb higher and higher, being careful not to fall. Once at the top, kill the Red Dantini and press the button. Then quickly go down the corridor, grabbing the crystals. Among them there is also the camouflaged blue crystal. You will come to another icy pool. If you pressed the button and were quick enough, a platform will drop down, allowing you to cross it. On the next platform there is the camouflaged green crystal. A little further on, you will find a chest with the fourth Gobbo. Then enter the door on the left.
Follow the tunnel, collecting the crystals. When you come to a frozen pond, go right, jumping on the platforms. You will come to a chest under some monkey bars. Don't break the crate, but jump on it to grab onto the monkey bars. Collect the suspended crystals; the last one is the camouflaged pink crystal. Go down and crush the chest to find more crystals. To reach two other crates you will have to take advantage of the crumbing platform over the pool. In the chest you will find the fifth Gobbo. Then use the two moving platforms to reach the other chest, which contains an extra life. Go back by jumping on the small platform. To the right of the gong are other platforms that will allow you to reach the crystal door. There are three boxes in front of it; all three contain clear crystals. Then enter the crystal door.
You will enter a room with four wells, from which pink snakes spring out. Right in the middle, there is a box containing the last Gobbo. Move carefully to reach it and to collect the crystals around it. If you are on the crate the snakes cannot reach you. After collecting everything, go through the short tunnel on the other side to reach the exit gong.