While in the "Monsters Cave" you usually have to kill the monsters to unlock the scene you are in. Instead, don't kill the monster and go to one of the corners and walk down. You can go somewhere else without killing the monsters.
Enter the editor tool and go to square 352 (counting from the top). Notice that it has all four potions and gold. Head to that square and go to a blue square. Click it you will notice that it will be the same as square 352.
To get to the island without cheating, when you are in the town called Windermeir, go all the way to the bottom of the screen (about two screens from the bottom right-hand side of the island). Wait some time and you will see a fish jumping up out of the water. The fish is actually a marker to the place where you can walk out on the water. The path on the water leads directly to the island with the large ducks on it. Also, by the time the Windermeir bridge is open, you should have enough strength, magic and defense to kill the monsters.