Spirit Oasis

The Spirit Oasis is a verdant garden located in a cave in the Northern Water Tribe's capital city at the North Pole. Although the land outside is perpetually frozen, the Spirit Oasis itself is warm. According to DVD commentary for "Seige of the North", it is a place where the Spirit World overlaps with the mortal world.

The Spirit Oasis first appeared in "The Siege of the North, Part 1", when Princess Yue brought Aang and Katara there in order to help Aang cross over into the Spirit World.

There is a pond in the middle of the Spirit Oasis, in which two koi fish (one black and one white) swim around each other in a circle. It is later revealed that these fish are Tui and La, the Moon and Ocean Spirits.

In Book 2, Pakku presents Katara with a vial of water from the Spirit Oasis, which is said to have "special properties". She keeps hold of the vial until the last episode of the season, "The Crossroads of Destiny", in which she uses the water in order to heal Aang after he had been fatally wounded by Azula's lightning.