Climb the climbing wall in front of you. You will notice a chest with two extra lives on the sides. First of all, you should break the crate and take the crystals it contains, because on the sides there are two Dark Dantini that will attack you, so you will do well to secure protection first. Then defeat the Dantinies and take the extra lives. Climb higher and collect the crystals around the pillar. Then climb the platforms that rotate around the pillar to reach the well at the top and jump into it.
Jump on the platform that leaps out of the quicksand in front of you and kill the Dark Dantini on the islet. On the right, jumping onto another platform, you will find an extra life. Go back and this time proceed in the other direction to reach the door. Enter it.
You will land directly on a platform, which will take you to a pillar. Taking advantage of the rotating platforms in front of you, you can reach three other pillars, on which there are as many chests. After crushing them all, go down to the central pillar at the bottom, where there is another chest. The chests all contain crystals. From here then, follow the path until you reach a well, jump into it.
Enter the pond in front of you. Collect the long row of crystals and the silver key at the bottom. You will meet two Dantini who will shoot you, try to eliminate them before they can hit you. Having taken the key, go back and enter the conduit to get out of the water.
Open the cage next to you and press the button. A platform will descend from above, right above the pond. Climb on it and the platform will lead you right to where the puzzle piece is. Grab it to complete the level. That's it, for the third island.