Atlantis is an underwater kingdom located somewhere deep in the Atlantic Ocean. It is home to the ancient, isolated, and highly advanced Atlantean culture. Originally part of a larger Atlantean empire, the present day Atlantis is now one of four surviving kingdoms after the Sinking of Atlantis.
Heavily isolated from the surface, the only way into Atlantis is a colossal glowing gate in front of an ancient bridge, guarded by customs and enforced by a massive array of powerful hydro-cannons.
- "We should've died. But we formed our own Unity: Amazons, Atlanteans, all the tribes of Man fought side by side. Warriors of legend, allies from other worlds, even the gods themselves, all acted as one, laying down their lives to fight Steppenwolf."
- ―Wonder Woman[src]During the First Invasion of Earth, the armies of Atlantis sided with the Amazons and the tribes of Mankind to fight off Steppenwolf's army and prevented the destruction of earth from the Apokoliptian conqueror. Aided by the Olympians and Yalan Gur, the armies of Earth fought off the invaders, at a heavy price.
However, the forces of Earth were successful in driving away the invasion, driving Steppenwolf mad in the process from his first defeat. Afterward, the Mother Boxes retrieved from the Apokoliptians were given to the armies of Earth for safeguarding, anticipating the eventual return of the forces.
The Fall of Atlantis
Founded by King Atlan, the empire of Atlantis at its peak was the most powerful and technologically advanced nation on the planet. Eventually Atlantis developed a series of new technologies centered upon their greatest achievement - the discovery of an inexhaustible source of energy, allowing the creation of machine walkers, advanced aircraft and the powerful Trident of Atlan. During a test of the Trident, a massive energy pulse violently radiated outward and destroyed Atlantis, causing it to sink into the sea with great loss of life.
As a result of the disaster, Atlantis and its empire splintered into seven successor kingdoms. Atlantis itself would form its own kingdom while others, such as Xebel, the Kingdom of the Deserters, the Fishermen, the Trench, the Brine, and the Missing Kingdom were formed from breakaway factions. As time went on, the seven Kingdoms would eventually undergo significant changes, either surviving, evolving to a new form, collapse or completely die out: Atlantis and Xebel would survive to the present day and retain the original characteristics of the ancient Atlanteans. The Kingdom of the Fishermen evolved to become fish-like and are considered adverse to conflict. The Kingdom of the Brine evolved into a crab-like and brutish people. The Kingdom of the Trench has regressed into savage creatures incapable of speech or intelligent thought. The Kingdom of the Deserters died out as the Sahara became a desert. The Missing Kingdom was reported to have completely disappeared, leading to it being called "lost".
The Fall had an unexpected side effect: the energy pulse affected the survivors biologically, causing them to gain the ability to breath underwater and superhuman strength needed to survive in the deep ocean. Alongside the biological improvements, the survivors safely harnessed the energy source to rebuild their destroyed civilization despite the Atlantean empire splintering.
As a result of the Fall, the despondent King Atlan took the Trident and went into exile, never to be seen again by anyone. His last words were copied onto a recording device and left clues to his whereabouts for future generations to find.
During his return to Earth, Steppenwolf invaded the Atlantean Vault in his quest to re-obtain and unify the Mother Boxes. There, he faced off against Mera and Aquaman, as well as a number of the Xebellian Guards. Despite their attempts to combat his invasion, Steppenwolf successfully retrieved the Mother Box, escaping through a Boom Tube. Aquaman decided to join the Justice League and Steppenwolf was later defeated.
King Orm attempted to declare war on the surface world and reuniting the Seven Kingdoms while doing it, but he failed and was arrested by Aquaman. After the war, the Seven Kingdoms reunited back into one.
- It was stated when Atlantis split into seven kingdoms, four of the seven are needed to ascend and attack. At the beginning of Aquaman, it had to be unanimous among the four remaining kingdoms to attack. This implies that this law is not focused on majority rules, but rather having a strong enough army to conquer the surface.