Anyway, swim to the island. Then you need to use the backs of the crocodiles to get across the water. There is an Idol to your right. Double-jump to the first croc, then hurry across his back and double-jump to the next croc, hurry across his back, and double-jump to the shoreline. Get the Idol and swim back to the island, then jump to the green box, double-jump to the crocodile, hurry across his back, and double-jump to the far shore.
If you take too long to get off the croc's back, he'll grab you in his jaws. The game will tell you how to escape this.