168. A Giant Snake Bares Its Fangs! The Survival Game Begins!(牙むく大蛇！遂に始まる生き残り合戦)
Canon
A giant python makes Luffy, Robin, Chopper and Zoro split while going to the ruins at the south. (Source: Wikipedia) Sky Island saga: Skypiea arc: (16/43)
Aired on: 10/11/2003
