Earth Kingdom harbor

The Earth Kingdom harbor is located in the southwestern part of the Earth Kingdom and serves as one of the Fire Nation's main naval points for ships to dock and resupply.

It seems that this harbor is a strategic location as it is in close proximity to the Southern Water Tribe and in a near enough point to provide the Fire Nation Army with troops and supplies for their further push into the Earth Kingdom, specifically to Omashu and Ba Sing Se. It remains under construction when first seen, noting the lack of buildings and fortifications and the number of tents.

Among its facilities is a large arena that hosts Agni Kais, or fire duels. It was at this arena that Prince Zuko fought and triumphed over his rival Commander Zhao upon their first encounter.

The leading officer in charge of the harbor was the newly appointed Commander Zhao, but it likely came under the command of another officer following Zhao's departure to capture the Avatar.

History
Zuko came to the harbor to have repairs on his ship after his first confrontation with the newly awakened Avatar Aang. Commander Zhao had some people interrogate the crew on Prince Zuko's damaged ship. It is after these interrogations that Commander Zhao found out the Avatar is still alive.

The Earth Kingdom harbor was not seen again, but due to the fact that the War ended in Earth Kingdom victory, this harbor was likely repossessed or shut down by the Earth Kingdom government.