Coralie and her friends are playing at the magic whirlpool, transporting to different oceans around the world to explore. Coralie travels to a kelp forest and discovers a map that seems to point to a treasure. The friends plan a treasure-hunting expedition, but the nosy Glenda is spying their plans. The mermaids are also worried about encountering dangerous animals like orcas or sharks in the kelp forest, and they try to make a plan to stay safe. But you never know what might happen out in the ocean!
Finn and Sage begin to wonder if there might be merfolk living in the ocean off the Scottish coast. They have been seeing strange sights in the water, and hearing a weird song that echoes off the cliffs. Sage begins to investigate in her kayak, but when Finn does a dangerous solo swim in the freezing waves, the two discover that the merfolk are more mysterious and strange than any legend they have ever heard. The merfolk are in danger from an old enemy, and they need help from the human children to save their little underwater colony.
The plot is incredibly slow. This could have been a short story, but it drags on and on. Once something finally does happen, it’s not that amazing. Finn and Sage are completely obsolete to the plans of the merfolk. They make a big deal about “helping”, but they never do anything that the merfolk couldn’t have just done themselves with less effort. A lot of fuss over nothing.
Marina and her father have just moved to a new underwater neighborhood, and Marina makes some new friends at school while her father researches rare fish in the area. Marina has to put up with a snobby girl at school, but she happily joins the Save the Sea Creatures club with her friends. However, Marina and her friends are frightened by a strange creature that is evidently destroying the local coral reef caves. They find some weird clues, but no one has sighted the creature. Can they solve the mystery before the damage gets worse?
I loved this cute book! The mermaid culture is wonderfully imaginative, and I thought it was so fun to learn about Marina and her friends. We also get some real life facts about interesting fish and conservation in the ocean. The mystery had me in complete suspense! I was puzzling and wondering, What is this big sea monster creature that is destroying the coral?