When they're passing by a brook with some rocks and waterfalls, Cleo falls into a cave. Cleo is okay, and Emma and Rikki come to her rescue, but they also can't get out. Now they're all trapped inside the cave, and are trying to find a way out. They walk through another corridor, and end up seeing a pool inside the volcano. Emma sees tide rings, and jumps into the pool to see if there's a way out. When she returns, she confirms that there's indeed a way out. That means that Cleo has got to swim, but she's afraid of water and she can't swim. Rikki convinces Cleo and when Cleo also jumps into the pool to swim out, the pool starts bubbling, and they see the full moon, shining through the volcano crater. They eventually swim out of the cave, and are found by the local water police.