There are all sorts of extraordinary creatures living on the reef under the sea. The plankton is dinner for the small fish and the small fish are dinner for the sharks and whales. Life is about knowing who might be after you, and enjoying the colours, the bubbles, the coral and the space of being under the sea. When visitors come from above the sea, they are unknown. Are they to be trusted? Should underwater creatures swim away fast, or could these visitors be bringing something good? A timid mermaid has been spotted by the divers who wish to take her to their world to prove that mermaids exist. Should she go with them or stay in the safety of the reef?