After being released from the iceberg, Aang's first request was to go penguin sledding with Katara, which she confusedly accepted. Later, upon seeing an otter penguin, a fascinated Aang immediately chased after it. Katara found him attempting to catch the animals, with little success. With Katara's help, he used fish to bait the penguins and, after being nearly trampled by the hungry creatures, managed to catch one on which he could go sledding. Katara caught a penguin for herself and joined Aang. As the two reached the end of the slope, their otter penguins tottered back up to the rest of the colony.
When Katara and Sokka returned to the Southern Water Tribe in 102 AG for the first time after the conclusion of the Hundred Year War, Katara spotted several young children sledding down a hill on otter penguins. Reminiscing about the day she first met Aang, she invited her brother to take an otter penguin and sled down the hill with her. Sokka complied though regretted his choice once he flew through the snow at high speeds and collided with a wooden beam at the bottom of the slope. As he sat in the snow, dazed due to the crash, his otter penguin happily waddled back to its group.
The otter penguin is an aquatic, flightless, mammal-like bird found mainly in the Southern Water Tribe. It has four flippers and is approximately as tall as an adolescent human. The creature's face is somewhat otter-like, with a small black nose and whiskers. It has a short neck that blends smoothly into its chest, and its feet are webbed. The otter penguin's coloration is counter-shaded, meaning its back, tail, flippers, and head are black, while its underbelly is white.
Although awkward on land, otter penguins are talented and graceful swimmers. They enjoy sliding down the icy shelves and hills of the poles, with or without a human passenger. Their oily feathers protect them from the cold water and also allow them to slide down icy slopes. Using the creature as a sled is a common recreational activity in both the Southern and Northern Water Tribes.
Otter penguins travel in large groups when on land. Though they will flee if chased, they can easily be lured with fish, which makes up most of its diet. It has one major natural predator, the tiger seal.
In a somewhat domesticated state, an otter penguin is capable of performing for entertainment purposes.
The otter penguin in the World of Avatar in many ways resembles the real world penguin, specifically the emperor penguin and other larger breeds. The primary differences between the otter penguin and the real world penguin are the former's two extra flippers and otter-like face, which lacks a beak.
- Although they are hybridized creatures, otter penguins are usually referred to as just penguins.
- In "The Boy in the Iceberg" with Avatar Extras bonus commentary, otter penguins are referred to as penguin-otters. The commentary reveals that the whiskers on otter penguins are inspired by the Fu Manchu mustache.
- In the Avatar: The Last Airbender video game, it is revealed that otter penguins are also used for sledding in the Northern Water Tribe, although the Avatar: The Last Airbender—The Art of the Animated Series states that they are native to the South Pole.
- From older Avatar: The Last Airbender official site, originally on Nick.com. Encyclopedia now broken, archived at The Lost Lore of Avatar Aang - Creature: Penguins.
- DiMartino, Michael Dante, Konietzko, Bryan (writers) & Filoni, Dave (director). (February 21, 2005). "The Boy in the Iceberg". Avatar: The Last Airbender. Season 1. Episode 1. Nickelodeon.
- DiMartino, Michael Dante, Konietzko, Bryan (writers) & Filoni, Dave (director). (February 21, 2005). "The Avatar Returns". Avatar: The Last Airbender. Season 1. Episode 2. Nickelodeon.
- DiMartino, Michael Dante; Konietzko, Bryan; Yang, Gene Luen (writer), Sasaki of Gurihiru (penciling, inking), Kawano of Gurihiru (colorist), Heisler, Michael; Comicraft (letterer). North and South Part One (September 27, 2016), Dark Horse Comics.
- Hedrick, Tim (writer) & Heck, Colin (director). (September 13, 2013). "Rebel Spirit". The Legend of Korra. Book Two: Spirits. Episode 1. Nickelodeon.