Marina Del Ray is a mermaid and the governess of King Triton's seven daughters, in charge of enforcing Triton's distant and formal parenting style following the death of his wife Queen Athena. She feels that she has been stuck as the governess for too long, and her primary motivation in the film is to take over Sebastian's job as the King's attaché by any means necessary.
She temporarily succeeds after getting Sebastian, Flounder, and their entire secret music band sent to prison (music was banned from Atlantica at the time), but upon learning of the gang's escape with Triton's youngest Ariel to find Athena's music box (the only object that will get Triton to change his mind), Marina resolves to kill all but Ariel by sending her electric eels after them (Ariel was banned from Atlantica by Marina).
While the eels battle the gang, Marina takes on Sebastian, who outsmarts her every move and ultimately gets her trapped inside a coral spike. Marina does not give up, however, and still tries to kill Sebastian by crushing him, but Ariel pushes her away. Marina is arrested and later sent to prison for her crimes.
Marina is extremely interested in clothing and fashion, and is the only merperson in the series who is seen wearing clothing over her fin to change its color and appearance.
Marina is a mean, selfish and traitorous mermaid who seeks power and control. She is shown to be an extremely funny and talkative woman. She is ever calculating, ever ambitious, and scheming as she seeks to get rid of Sebastian whom she despises the most. She is also indeed sly, ruthless and manipulative in nature.
Marina Del Ray summoning her Electric Eels to fetch Sebastian.
Marina's last name is the same as Lana Del Rey, the singer who sang "Once Upon a Dream" in the 2014 Disney live action film Maleficent.
When she fights with Sebastian, it resembles the fights between Prudence and the Grand Duke to impress The King in Cinderella II: Dreams Come True.
When compared to her predecessors, Marina is only a villain in the loosest sense of the word (all she wanted was a promotion, whereas the villains before her wanted the whole kingdom under their thumb). However, Marina is still considered a villain due letting her pet electric eels chase Ariel and her friends to eat them. Unlike Ursula and Morgana, Marina is a mermaid (just like the film's protagonist Ariel).
Indeed, this is one of the main reasons for which Marina has not been well received by fans, becoming an object of scorn given that many fans deem her predecessors were genuine threats.
Marina is the second main villain in the franchise to have eels as henchmen (the first being Ursula). However, unlike Flotsam and Jetsam, her eels never talk and they are electric eels instead of moray eels.
It is shown that when ever Marina changes her clothes, her fins and tail also change color as well. This could be either an animation error, or it is possible that mermaids can change the colors of their fins and tails in some unknown way.
She could also be putting fabric over her tail, and we never see the real color.
Marina has some similarities to Yzma. Aside from having some physical similarities to Yzma, she also had a similar motive towards her villainy: Both were the result of wrongs committed against them by one of the main characters (Sebastian's berating and degrading of Marina, and Kuzco's callously firing Yzma despite loyal servitude to Kuzco's dynasty for several years).
Her name is the same name of a city in California.