|“||Face it, Triton, you're all washed up!||„|
|~ Undertow to King Triton.|
|“||Going somewhere, boys?||„|
|~ Undertow's last words before he attempts to kill Tip and Dash.|
Undertow is the secondary antagonist of Disney's 2000 direct-to-video animated sequel film The Little Mermaid II: Return to the Sea, the sequel to Disney's twenty-eighth full-length animated feature film The Little Mermaid (which is based on the 1837 Danish fairytale of the same name by the late Hans Christian Andersen). He is Morgana's pet Megalodon-sized great white/tiger shark hybrid and right-hand man.
He was voiced by Clancy Brown, who also played Viking Lofgren in the 1983 film Bad Boys, Byron Hadley in The Shawshank Redemption, The Kurgan in Highlander, Lex Luthor in the Animated DC Universe, Doctor Neo Cortex in the Crash Bandicoot video game series, General McGuffin in Wander Over Yonder, Harry Bordon in Cast a Deadly Spell, Parallax in Green Lantern, and Mr. Krabs in Nickelodeon's SpongeBob SquarePants.
For the next twelve years, Undertow soon becomes obsessed with becoming a full-sized shark again, but Morgana's magic does not work, and he remains small throughout most of the film. He helps to deceive the older Melody into joining Morgana and getting Triton's trident.
When Morgana finally gets the trident, she turns Undertow back into his original size at an opportune time, much to his complete delight. He is sent after the penguin/walrus duo, Tip, and Dash when they go to rescue Melody, and he attempts to eat them. Tip and Dash, however, manage to hold him off and steer him into an ice wall that served as Melody's prison.
Undertow shattered through the ice and smashed against the rock wall behind it, breaking all of his (very un-shark-like) teeth in the process. It's completely unknown what happened to Undertow following this, but it could be possible that he escaped before Morgana's lair sank down, or if that wasn't the case, he was presumably crushed or dragged with the lair to the depths of the ocean to his death.
- Since sharks always grow their teeth when they fall out, it is possible Undertow survived.
- Undertow (as a shark) shares similarities with Glut the Shark from the original film. Both sharks are villains and both tried to eat the protagonists (Flounder and Ariel in Glut's case and Melody, Tip and Dash in Undertow's case), but failed. However, they also have some differences: Glut cannot talk, and Undertow can talk; Glut is a minor antagonist, and Undertow is the secondary antagonist.