|“||Face it Triton, you're all washed up!||„|
|~ Undertow to King Triton.|
He is summoned by Morgana to eat the baby princess Melody, but King Triton turns him into a small, piranha-like fish, much to his chagrin. For the next 12 years, Undertow soon becomes obsessed with becoming a full-sized shark again, but Morgana's magic doesn't 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 is unknown if the impact killed him or not.
- Since sharks always grow their teeth when they fall out, it is possible Undertow survived.