Zeena and the Mermaid — Victoria Zigler

The adventures of Zeena and Saarik have already taken them through the woods and up the mountains. Now they're answering a plea for help from a mermaid named Naia. With the help of both Naia's magic and Zeena's own magic, the two friends head on an underwater quest to free the water fairy, Lana, and make the ocean safe once more. This is the third book in the “Zeena Dragon Fae” series. The books in the series are as follows: 1. Zeena And The Dryad 2. Zeena And The Gryphon 3. Zeena And The Mermaid 4. Zeena And The Phoenix