Luffin (ルフィン Rufin) is one of the key characters in the Nobita's Great Adventure in the South Seas.
When Nobita drowned, he was saved by Luffin. It brings Nobita in Tomos island with Jack. The two befriend and Nobita learns the dolphin's name, Luffin, as well as the fact that Jack is also separated from his family, like himself. Later in the movie, Luffin catches glimpses of the other torn half of treasure map owned by Nobita, he quickly leads Nobita and Jack to a 22nd-century-underground facility, but are captured by security guards.
Luffin is taken to be experimented, while Nobita and Jack are thrown to jail and reunited with Doraemon's pirate company. After they escaped, Nobita and his friends go to break the control system and free Luffin. Later, it was revealed that Luffin is a secret agent who summoned the Time Patrols to capture Cash.