Maya (best friend)
Aquata is a mermaid, Sirena's sister, and a member of the pod. She follows the rules and leaves Mako Island with the pod, but before she goes, she gives Sirena her Moon Ring. Aquata and Sirena appear to have a very close relationship and she is visibly upset that she had to leave her sister and talked to the mermaid council. Sirena was so upset that Aquata was leaving.
Aquata has the ability to swim at super speed of 600km/h, as shown in Aquata Returns.
All mermaids can make themselves invisible.