Emma dedicated most of her free time training and competing for her swim team, and had won countless trophies for it. Unfortunately, due to protecting her mermaid secret, she had to quit the team. Out of all three girls, Emma grew up in a more stable environment as her father is a business man in sales and financial development. Her mother, Lisa Gilbert, was once a junior lifeguard and currently collects crystal figurines. Despite growing up in a more wealthier lifestyle than her friends, Emma lacks the personality of a snob. Unlike her popular classmate, Miriam Kent, Emma and her brother were taught to be respectful and truthful to one another. Used to her perfect family lifestyle, Emma admits feeling guilty whenever she had to lie to her brother or her parents. Unlike her friend, Cleo Sertori who does not get along with her younger sibling, Emma shares a close relationship with her younger sibling, Elliot, and at often times she would try to comfort and reassure him whenever he's unhappy. Although several times, they still got on each other nerves and argue. Emma is Tall, athletic, and naturally fair-skinned with golden-blonde hair and light blue eyes. Mermaid Appearance: Transforms into a mermaid with long, wavy blonde hair worn down. She has a coppery-orange tail that fades to red at the tip. Style: Favors blue and white clothing, matching her ice-related powers. Emma has the ability to freeze water.

Rikki grew up in a struggling environment, Rikki lacks the personality of a snob and she doesn't like being around one, such as Miriam Kent and Zane Bennett. Since she was little, Rikki has been used to people not liking her, so when people express their affections and kindness towards her, she feels uncomfortable and "fenced in". Before moving into the Gold Coast, Rikki was used to She likes to be alone- particularly until she saved Cleo from being drifted in Zane's boat that Cleo opened up to her and offered Rikki her friendship as well as Emma's. Rikki Chadwick is portrayed as a slender teenager with wavy, platinum-blonde hair that falls just past her shoulders and striking, dark-lashed sky-blue eyes. She has fair, unblemished skin and wears rosy, plump lips. As a mermaid, her tail is a vibrant orange-red. Rikki has the ability to boil water.

Cleo Sertori grew up in a family that consisted of herself, her father Donald Sertori, her mother Bev Sertori, and her younger sister Kim. Don is a successful fisherman and owns three fishing boats. He can employ others into his service. While Don works a lot at the harbor, Cleo's mother stays at home as a housewife. When she was a little older, she met Emma and the two of them became good friends. Cleo knows Emma very well, and she also knows that Emma is always prepared. Cleo's family is not as rich as Emma's family, but Cleo’s father's fishing job enables them to have enough money to live in a house nearby the canal. Cleo is an lactose intolerant. Unlike Emma, Cleo doesn't get along with her younger sister Kim. They argue very frequently, which oftentimes requires their parents’ intervention to reach a medium. Human Form Hair & Eyes: Mid-back to long brown hair that is frequently styled into buns, braids, or ponytails. She has warm hazel eyes. Fashion Style: Soft, feminine, and Y2K-inspired. Cleo is considered the "girly girl" of the group, favoring a bright color palette of pinks, purples, and teals. She is known for layering tops and wearing more skirts than the other girls, accessorizing with beads and unique textures. Jewelry: She wears a distinct purple-stoned locket identical to the other mermaids, and later in the series, a blue crystal necklace. Mermaid Form Tail: Features an orange-scaled tail and matching top initially. After a transformative full moon in the Moon Pool, her tail and top shift to a pinkish-purple hue. Hair: Unlike her human form, her hair is worn completely loose and flowing when she is a mermaid. Cleo has the ability to control water.