Ozai's airship base was a Fire Nationmilitary settlement located in a large crater on a remote volcanic island off the coast of the Earth Kingdom. The Fire Nation used the island to house the construction and preparation of a fleet of airships in anticipation of the return of Sozin's Comet. The location of the island suggests it was chosen for its proximity to the Earth Kingdom mainland as a strategical advantage in Fire LordOzai's planned destruction of the Earth Kingdom. The base itself was capable of accommodating over a dozen airships as well as all the associated crew and military, amounting to thousands of inhabitants at the time prior to the fleet's departure.
Prior to the Battle at Wulong Forest, Toph, Suki, and Sokka arrived at the shore of the island, but realized that they were too late to intercept the fleet. As the airship armada began to depart, Toph launched the trio onto the nearest airship, which they were able to commandeer and use to stage a sabotage of the entire fleet.