Run Idate Run! Nagi Island Awaits!

is episode 104 of the original Naruto anime.

Synopsis
Aoi taunts Idate and attacks him. Team 7, who are still swimming for the island, are attacked underwater by the Rain ninja. Using the first step of training for the Rasengan, Naruto creates a huge whirlpool that saves them. They then try to rescue Idate, but prove to be no match for Aoi, who poisons them and leaves. Sakura gives them all medicine Tsunade had given her, and they seek shelter in a cave. Idate explains that he was once a Leaf ninja, but was tricked by Aoi into betraying the village after failing the Chūnin Exam.