The Boy in the Iceberg.Katara and Sokka, two siblings from the Southern Water Tribe, discover a boy trapped inside an iceberg floating on the sea. They free him and he introduces himself as Aang, an Airbender of the Air Nomads—a culture believed to be extinct for 100 years. Aang and his flying six-legged sky bison, Appa, accompany Katara and Sokka to their village. Meanwhile, Prince Zuko of the Fire Nation, accompanied by his uncle Iroh, is patrolling the surrounding waters in search of the Avatar, a fabled immensely powerful bender who can bend all four elements. Katara confides in Aang that she is a waterbender, but there are no other waterbenders in the Southern Water Tribe to teach her. Aang promises to take her to the Northern Water Tribe to find a teacher. A chance encounter with an abandoned Fire Nation ship reveals that Aang is unaware of the war that the Fire Nation has waged against the other nations of the world for 100 years; from this they deduce that Aang must have been frozen for at least that long. The pair accidentally set off a signal flare on the ship, alerting Zuko, who already suspects the Avatar is nearby.