The Blue Mermaid is a character who first appeared in "The Legend of the Blue Mermaid"
The Blue Mermaid lives near Umi City in the sea. The amazing thing about the Blue Mermaid is that her tail glows. One day, Squiddy The Squid captured the Blue Mermaid and took her to his sand castle, so she calls for Team Umizoomi to save her. To make sure that they get to the right place, she sends a trail of her scales to the castle. Milli, Geo, and Bot follow the scales to the sand castle to save the Blue Mermaid. When the Blue Mermaid was finally saved, Squiddy reveals that he is afraid of the dark. The Blue Mermaid gives Squiddy one of her scales so he wouldn't feel afraid and shy.
This character has no relationship from Disney's "The Little Mermaid" character Ariel.