Marina is a compassionate young mermaid and unlike the mermaids shown in the first two films, she is helpful and unselfish. She joins Jake and the crew on occasions and when she does it makes all the difference. Marina seems to have feelings for Jake. She has a pet starfish named Sandy who she cares for and loves deeply. Sometimes when she's excited she does a little giggle. She is also shown to have the ability to communicate with the creatures of the Never Sea ("Bucky's Anchor Aweigh!").
Marina is said to be the undersea pirate who helps Jake with the rules of the water and comes to help when Jake and his crew deal with major water adventures. She first appeared giving Jake surfing lessons in the episode "Surfin' Turf" and joined him to save their surfboard from Captain Hook. She played a supporting role in the episode "Jake's Starfish Search", where she asks Jake to watch her starfish while she goes to her undersea ballet class.
She played a large role in the episode "Save the Coral Cove!" Captain Hook and Smee are planning to dig up the bottom of the sea destroying many sea creatures' homes. She goes to Jake for help, but Hook ends up being chased away by an octopus and later his machine that somehow gains a mind of its own. The machine attempts to attack Bucky, but Marina ties a cord attached to it onto a shipwreck but it doesn't hold. Izzy defeats the machine and the cove is safe.
In the episode "Pirate Rock!", Marina overheard Jake's crew performing their song. She told them they should perform a show, much to the pirate's delight. She left to gather their friends to watch them perform at Pirate Rock. At the end, Marina was seen with the other friends, watching the pirates perform.
In "It's a Winter Never Land!", Marina and some other friends got together with Jake and his crew to celebrate a Christmas themed holiday. At the end of the episode, Captain Hook successfully stole all the gifts and the tree, however, Marina convinces her friends that their friendship is the only thing they need to have a fun holiday.
In "Bucky's Anchor Aweigh!", Marina and the pirates get together to present a gift to the ship Bucky, a golden anchor. However, Hook and his crew steal the anchor having Bucky chasing after them. Even though Bucky left, he left the crew behind. Marina suggests the pirates use an old washed up dingy that fortunately still floats. With the help of their octopus friend, they manage to reunite with Bucky and retrieve the anchor.
In the episode The Mermiad's Song it's reaveled Marina has a younger sister named Stormy.
Marina makes a speaking cameo appearance along with her sister Stormy, Sandy the Starfish and the rest of the Never Land friends took part in Jake's birthday celebration in "Jake's Birthday Bash!"
Marina and Stormy make a brief cameo appearance in the episode "Captain Who?" When Captain Hook gets a whiff of the Forget-Me Flowers he forgets he is the captain of his crew Sharky, Bones and Mr. Smee enlist Jake and crew to help jog his memory. Marina plays a minor role in the episode "Seahorse Saddle-Up!" as the host of the seahorse race.
Marina makes a non speaking cameo appearance in the episode "Trading Treasures", Marina appears at the end of the episode attending Queen Coralie's Fin and Frolic dance party dancing with two mermaids.
In the episode "The Mermaid Queen's Voice", Queen Coralie was set to host and preform a concert at Mermaid Lagoon but come down with laryngitis right before the concert begins.Marina appears at her queen's side speaking on her behalf when they ask Jake and his crew to help cure Queen Coralie.Marina was present when Jake and his crew return to Mermaid Lagoon with the Fa la la water that would cure Queen Coralie. as Jake was about to hand the bottle to Queen Coralie,Captain Hook swoops in and stealing the bottle. This is short lived as Hook gloats the captain is quickly scolded by his mother who arrives at the lagoon as Queen Coralie's guest.Marina again speaking for her queen revealed that Coralie only wanted to preform her concert in Mama Hook's honor.Marina is last seen amongst Jake and their Never Land friends enjoying the duet between Queen Coralie and Captain Hook.
Marina reappears in the episode "A Royal Misunderstanding", as one of the dancers in Queen Coralie's ballet performances but finds herself caught in the middle of a dispute between Queen Coralie and King Crab. Fortunately, Jake and his crew soon arrive to watch both the crabs race and mermaids dance to suggest both Coralie and King Crab share the beach. However, both Captain Hook also desired the location for his date with Red Jessica.
Marina reappears in the episode "Sleeping Mermaid", She joins Jake and his crew accompanied by Queen Coralie as they collect seashells on the beach, the queen notice a stone message on rock wall warning the dangers of the Spell Shell which has the power to put anyone into a deep sleep. Marina soon discovers the Spell Shell, but as she hands the shell to her queen it puts Coralie into a deep sleep. The only way to reverse the spell is if Jake and his crew must convince Captain Hook to help. Hook reluctantly agrees to assist the mermaid queen in order to claim the huge pearl Marina offers for his reward.
Marina makes a brief appearance in "Jake and the Never Land Pirates: Battle for the Book", Peter Pan comes to the mermaids assistance dealing with a vicious sea beast that evades Mermaid Lagoon.
- “And I actually think that she has a little romance with Jake budding.”
- ―Ariel Winter at an early interview for the show.
Marina is shown to have romantic feelings toward Jake. She seems to care for Jake's safety more than anyone else's. She also seems to create a small change in Jake's personality. Marina became very excited when Jake joined her in the water in the episode "Surfin Turf", and even had a slight blush possibly because of the crush. In one episode when Marina asked Jake to watch her pet starfish, she asked in a flirtatious tone.
Marina's love was confirmed when voice actress Ariel Winter stated during an interview, "I think Marina may have a little crush on Jake. I've seen that a bit throughout the script. She's always there to help him in her sweetest voice...."
- Marina's debut episode "Surfin Turf" has become one of the series' most recognizable premieres.
- Marina's heroine side in "Save the Coral Cove!" has a few similarities to Ariel of The Little Mermaid, rendering the first name of her voice actress still more appropriate.
- Despite her actress confirming Marina's crush on Jake, the creators have yet to confirm this or not.
- The flying surfboard ride at the end of "Surfin Turf" is reminiscent of the flying carpet ride in Aladdin.
- Marina only has a cameo at the end of Jake and the Never Land Pirates: Peter Pan Returns, despite being the first hour-long episode of the series. This also happens in "Jake and the Never Land Pirates: Battle for the Book".
- Marina is the fifth main character to have a solo song ("Undersea Bucky!"), the first being Izzy ("Surfin Turf"), the second being Cubby ("The Golden Twilight Treasure"), the third being Captain Hook ("Treasure Show and Tell"), and the fourth being Peter Pan (Jake and the Never Land Pirates: Peter Pan Returns).
- Marina's being so sweet and kind, when compared to the other mermaids, invites comparison with Syrena from Pirates of the Caribbean: On Stranger Tides.