The royal barge is a Fire Nation royal-class ship commonly used as a means of transportation by the Fire Nation Royal Family. Many ships of this class are customized by their owners in order to meet their preferences and needs. For example, Princess Azula used a massive, intimidating, and heavily ornamented barge, while Fire Lord Zuko preferred a smaller but faster variant of this class.
As one of the most technologically advanced ships in the fleet, the royal barge, specifically the one used by Azula, was the pride of the Fire Nation Navy. The ship was specially made for Azula and no expense was spared for its construction.
Azula used her royal barge when she traveled to the Earth Kingdom in order to capture the traitors Zuko and Iroh on Fire Lord Ozai's orders. On deck, she made clear to her bodyguards that they were not to hesitate to attack a member of the royal family if they wanted to live. Soon after she dismissed the guards, the captain approached the princess, saying that the tides would not allow them to bring the ship into port before nightfall. It became apparent that Azula ruled her crew with an iron fist when she forced the captain to bring the ship in anyway, threatening to kill him if he did not. At nightfall, Azula practiced her lightning generation on deck under the watchful eyes of her teachers, Lo and Li.
After docking in the port, Azula tracked down her brother and uncle and convinced Zuko to journey back to the Fire Nation with her on her ship. Iroh, skeptical about Azula's intentions, joined him in order to keep an eye on Zuko's safety. When the two arrived at the docks, they walked through an honorary guard formed by Azula's crew and were warmly welcomed by the princess, who ordered the captain to set course for home. When the captain relayed the orders to the guards, he misspoke, saying that they were "taking the prisoners home". Zuko realized her true intentions, immediately taking action and pushing the captain overboard in order to get on deck where Azula was, while Iroh took care of Azula's bodyguards. The two siblings fought on deck, Azula clearly the better fighter. However, when she prepared to finish the fight with a bolt of lightning, Iroh intervened by redirecting the bolt and throwing his niece overboard, allowing the two to escape. Azula later discarded her ship as main means of transportation after Lo and Li pointed out that it might no longer be wise to travel with the Royal Procession if she intended to keep the element of surprise.
The Fire Nation princess used her ship again to travel back home with Zuko, Mai, and Ty Lee after they had conquered the Earth Kingdom capital of Ba Sing Se. They also brought Iroh along with them as a prisoner after he betrayed his niece and nephew by attacking them in the Crystal Catacombs in order to allow Katara to escape with Aang's body.
The royal barge used by Azula was much larger and faster than her brother's ship, which was a much older model. As a testament to its royalty and high rank, the ship boasted gold on the roof of its tower and on the two-pronged bow.