Black Cliffs

The Black Cliffs are a series of high coastal cliff-face and stacks located just offshore of an uninhabited inner island of the Fire Nation. Their formation creates a natural secluded bay, which Sokka and Hakoda designated a rendezvous point prior to the Invasion, as here they were able to easily harbor and hide their naval force. The Black Cliffs take their name from the dark volcanic rock of which they are formed.

History
Team Avatar camped out on the island in the four days preceding the invasion, during which time Aang went into a state of sleepless restlessness and panic as he felt that he was not ready to face the Fire Lord. After many failed attempts to calm Aang's mind, the group eventually restored his confidence and sanity through a few words of reassurance and allowed to him finally sleep by constructing him a bed of koala sheep wool. On the day of the invasion, the naval force, led by Hakoda, arrived at the bay. The invasion force was briefed on the details of the invasion plan at the foot of the cliffs, after which they prepared for battle and departed for the Fire Nation Capital along with Team Avatar.

Fauna
The Black Cliffs are only known to be inhabited by two types of animals. Both koala sheep and boarcupines call the Black Cliffs home.

Trivia

 * The Black Cliffs share a similar name to the real-world Black Hills, a small chain of mountains in South Dakota, United States, and is home to Mt. Rushmore, among other monuments.