Tom and Sam are in a small boat. The sea is calm, and the sun is warm. They see a big rock with a hole. They stop the boat and look inside. It is a crystal cave!
Inside the cave, the walls shine with many colors. A big shark swims in the water. Tom and Sam are scared, but the shark is friendly. The shark says, "My name is Finn. A big storm is coming. You can stay here, but you must be patient."