An Otter Penguin
Otter penguins are passive and rideable mobs found in icy biomes. By right-clicking you can go sledding on them. Sledding is a great way to move around as otter penguins are extremely fast!
Breeding
Otter penguins are able to breed through the use of raw fish. Simply feed them enough fish until hearts appear on the top of their head. When two otter penguins are in "love mode", they can create a baby otter penguin.
Drops
Otter penguins drop 0-2 raw fish and possibly raw salmon. They also have a 25% chance to drop a waterbending scroll. They can be used to farm these waterbending scrolls.