She has an hourglass figure and fair skin. In her childhood, she used to wear a lavender tube top. Her lips were the same color as her skin. From the waist down, she has a green tail with paler green, translucent fins and wears a brassiere made out of lavender seashells. She has large, deep aqua blue eyes and full red lips. Her most defining feature is her long, red hair that matches the color of her lips. In Little Mermaid's Island, her seashell bra looks more like a strapless top that covers her belly.
- Superhuman Strength: She is known to have at least a certain degree of superhuman strength, as she was able to move away an underwater boulder blocking her grotto with relative ease.
- Underwater Breathing: As a mermaid, she is also able to metabolize oxygen from the water, which negates the need to surface, though she is certainly more than capable of breathing on land.
- Speed Swimming: Also, she is capable of swimming at a much faster rate than humans or even certain marine creatures in terms of undersea travel, or sea travel as a whole due to her half-marine status. Like dolphins, she is capable of leaping out of water at great heights. For example, she was able to get to Triton's Greenland Palace from Denmark (the implied location of Eric's kingdom) in less than a day, as well as getting from Atlantica to Norway in the episode "Metal Fish" in a similar time fashion.
- Because of her being a mermaid, she is also capable of speaking with aquatic fauna. She retains her ability even in human form, but whether her abilities of superhuman strength and endurance were retained upon becoming human is debatable.
In the Ocean, Orphaned grown into a Teenage Mermaid, Marina and her fish friend Pablo more commonly known as Flounder swim through a shipwreck where they salvage human items. During their adventure, the two are attacked by a shark, but Marina manages to outwit the vicious creature with the help of Poseidon by going through Ariel's Grotto which the Harvester accidently destroyed it before king triton did wich caused Ariel down in tears, and an ashamed Triton leaves the grotto. After escaping the shark, Marina and Pablo swim up to the surface where they speak to Shuttle to identify human objects. Shuttle misidentifies a fork as a "dinglehopper" used to straighten their hairs and a pipe as a "snarfblatt" used to make music to attract whales. When marina searches for treasure in the sunken ships, the Leviathan spots Marina and Pablo swimming about in it's Territory. He immediately attacks Flounder and begins a chase going through the Tunnel to the Entrance to Atlantis. Unfortunately, Marina manages to outwit the Creature and the Leviathan sleeps while guarding Atlantis. Meanwhile, while Kaede searches for the Terrible Dog Fish, Marina tearfully swims off to her secret grotto, where her collection of human objects, from books to other regular objects, such as globes, mugs and chests of jewels, is kept. She feels that collecting human objects isn't enough and gets more curious about the world above the ocean, even expressing her desire to actually live among the Sea Creatures. The mood is quickly broken by Maximus, more commonly known as Sebastian crashing in, and threatening to reveal Marina's grotto to the king triton. Ariel attempts to reason with him, but before anything could be resolved in the conflict, a large object is seen floating overhead blocking moonlight from the grotto roof.
Marina, being ever curious, swam to the surface to figure out what this massive object was. The object proves to be a human ship, shooting fireworks into the night sky. Marina swims toward the vessel and climbs aboard to behold dancing seamen. Marina learns that the humans aboard are celebrating the birthday of their prince; one creature that catches her eye is Max, the sheepdog who takes a liking to Marina. But Marina is left enamored when she sees the dog's master, prince Eric. She then spots a male human by the name of Kaede was escaping with it's Family from the Terrible Dog Fish and remarks to Shuttle how she has never seen a human this close before. Just then, as the Terrible Dog Fish tries to catch Kaede and his Parents, Without warning, the Giant Whale was sweeping up both ship and crew violently in a volley of wind and water. Marina is thrown off the vessel but managed to catch sight of the ship being struck by lightning. When the ship crashes into a gaggle of rocks, the crew is sent overboard, along with the statue of Eric. Though they all made it to the lifeboats, Eric discovers that Max is still on the burning vessel, and goes off to rescue him. While Eric managed to get Max to safety, he is unable to save himself when a massive explosion caused by the Terrible Dog Fish blows him away, Marina looks around for and finds Kaede's Mother and Uncle unconscious in the sea. She carries Eric and Kaede's Mother to the shore where she founds Kaede dead after escaping the Terrible Dog Fish. In the Aftermath, Marina sings the Part of Your World about entering the Kaede's Original World before returning to her Grotto. In the Grotto, two eels, Flatsam and Metsam, appear to convince Marina to see their master Cortana the Sea Witch, who may have the power to make Marina's dream come true. Marina reluctantly follows Flatsam and Metsam to Cortana's fortress. Marina nervously and fearfully enters the fortress, and Cortana calls for her. The sea witch, who knows that is in love with a human through spying on her via Flotsam and Jetsam. Cortana explains the deal to Marina: Marina will become human for Eight days, during which she must get a kiss of true love from Kaede before the sun sets on the eighth day in order to stay human; otherwise, Marina will turn back into a mermaid and will be bond to Cortana forever. Cortana furtherer states that as part of the deal, Marina must give up her voice in order to become human with the Telepathic Voice. Marina thinking that is her only change to be with Kaede, accepts the deal as she signs a contract conjured by Cortana. The sea witch then orders Marina to sing for her and summons magical hands to rip out Marina's voice, which is then sealed into a Jar and leaves it to her telepathic voice. Unfortunately, the prince does not know Maria is the one who saved him. He mistakenly believes it to be the raven-haired girl who discovered him on the beach after Marina had rescued him. Since he cannot find her, he wishes to marry Marina. Filled with joy, the prince remembers now that she was, in fact, the one who saved him. Maria and Kaiser marry on a ship The sea witch takes Maria's voice in exchange for legs. Tearfully bidding farewell to her family and to Fritz, she goes on to the surface. The following morning, she is discovered by the prince. Maria lives with the prince for a month, in that time their bond grows strong. The Prince calls her "Princess Mermaid" because she came to him from the sea and cannot tell him her own name as she is now mute. The Prince tells her how his parents want him marry a princess from another kingdom. However, the only girl he wants to marry is the one who saved his life. Unfortunately, the prince does not know Marina is the one who saved him. He mistakenly believes it to be the raven-haired girl who discovered him on the beach after Marina had rescued him. Since he cannot find her, he wishes to marry Marina. Filled with joy, the prince remembers now that she was, in fact, the one who saved him. Maria and Kaiser marry on a ship Marina is then turned into a human and is helped to the shore by Flounder and Maximus due to her inability to swim. At the shore, Marina is found by Shippuden and her sheepdog Max, who leads his master to her after Kaede was revive. Nevertheless, Kaede takes Marina to his palace, where Marina takes a bath and gets dressed for the dinner. As Kaede, his manservant and maid join her, Marina notices a fork and uses it to comb her hair, making the three dumbfounded, which makes her embarrassed. Noticing Manservant's pipe, Marina takes it and, thinking it as a musical instrument, blows the contents into Manservant's face, and Kaede laughs at Manservant's face covered with ash. After manservant's wipes his face and dinner is served, he suggests that Kaede take Marina out on a kingdom tour, which Marina accepts. The next day, Kaede takes Marina out to show her his kingdom. During the tour, he teaches her to dance. That evening, Kaede and Marina spend time in a lagoon, riding in a rowboat rowed by Kaede. In order to get the two to kiss, Sebastian leads some animals in the lagoon to create the mood with music and his song Kiss the Girl. With the Promise by the Sea Witch being kept, Marina's Transformations was infinite (which is Human and Mermaid Forms). Noticing how Marins loves Kaede, Cortana opens the seal and bestows Marina's voice to her permanently that Cortana became one of Kaede's Allies. Soon, Marina and Kaede, now married, have a wedding on the wedding ship attended by Kaede's loyal subjects onboard. Marina bids farewell to Shuttle and Pablo and Cortana gives her a heartwarming handshake and the hug before happily sailing away with Kaede. Jim and Shippuden and Sasuke is then awarded with a certified 14-karat conscience badge.