Naydra is one of three legendary dragons seen in Legend of Zelda: Breath of the Wild.
Naydra is a massive dragon that highly resembles a classic eastern dragon. It's body is long, white and serpentine, with rows of rock-like blue spikes on it's back and tail. There are three pairs of small legs on it's body, and it's head is adorned with several spike-like horns.
Little is known about Naydra, and most Hylians only know of him in legend. All that's known is that Naydra is spirit of ice that took the form of a dragon to watch over Hyrule. At some point after Ganon's rise to power, Naydra was corrupted by the evil substance known as Malice, but was eventually freed by the hero Link.
Naydra is initially seen at the peak of Mount Lanaryu. After being freed, it will fly over southeast Hyrule on the same path every day.
Much of what Naydra can do is unknown. The creature takes little interest in monsters, and bears no ill will towards Hylians or other races. It also cannot be killed, and will simply fly up into the sky when attacked. However, Naydra constantly produce powerful updrafts around it, as well as orbs of ice that can be dangerous for anyone who strays too close to the beast.
The scales, claws, fangs, and horns of Naydra can be used to create powerful elixirs. Its scale is also required for entering the shrine at the Spring of Wisdom, which can be obtained easily after releasing it from the Malice, as it will be still waiting for Link to do so.