Looking forward to more.
I like this. My thoughts on it...
Okay, the animation is excellent, though I am not to fawn of the chosen colors. It seems a bit half down. The background is kinda blurry and lacking in detail. Not sure if that was your intention.
Things to Improve: Also I would like to see bigger splashes, and ripples in the water. I would also like to see the wake coming off the boat they are traveling on. What happened to their boat... did it just disappear? I say work more on water effects, which is one of the hardest things to animate. I would also like to see the villain's powers as well. Right now they seem like punching bags. Show people as to why they are on the Island as well. Make them into an obstacle for the characters to overcome, unless they are suppose to be the comic relief, then that is cool.
Things to keep: I like the story idea and it is entertaining to watch. The animations are pretty good and it looks like you have the basic understand of animating. The ending was pretty funny. I like the characters as well. The "I'm too cool" guy, The annoying girl, and the cowardly boy. Great mix of characters. The villains are well designed.