Avatar: The Last Airbender - Season 2 - Eps 10: The Library
When Aang and his friends find a professor who knows of a library that contains information about the world, Sokka decides to go there to hopefully find some information to use against the Fire Nation. The library is guarded by the knowledge spirit, Wan Shi Tong, who doesn't welcome humans into his library, because he believes they only seek information for evil purposes. When Wan Shi Tong discovers Sokka wasn't being truthful with him, he begins to sink the library, bringing the kids down with it.
About Avatar: The Last Airbender

Title: Avatar: The Last Airbender
First Air Date: 2005-02-21
Last Air Date: 2008-07-19
Status: Ended
Rating: 8.7/10 (from 4263 votes)
Language: EN
Seasons: 4
Total Episodes: 61
Network: Nickelodeon
Genres: Animation, Action & Adventure, Sci-Fi & Fantasy
Production Companies: Nickelodeon Animation Studio, JM Animation, DR Movie, Moi Animation, Nickelodeon Productions
Synopsis
In a war-torn world of elemental magic, a young boy reawakens to undertake a dangerous mystic quest to fulfill his destiny as the Avatar, and bring peace to the world.
Cast

Zach Tyler Eisen
Aang (voice)

Mae Whitman
Katara (voice)

Jack De Sena
Sokka (voice)

Dante Basco
Zuko (voice)

Jessie Flower
Toph Beifong (voice)

Greg Baldwin
Iroh (voice)

Dee Bradley Baker
Appa / Momo (voice)

Grey DeLisle
Azula (voice)

Cricket Leigh
Mai (voice)

Olivia Hack
Ty Lee (voice)