This article contains spoilers from the most recent DCEU film. You have been warned.
Atlantis is an underwater kingdom located deep underwater somewhere 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 massive, glowing gate in front of an ancient bridge guarded by customs and enforced by a massive array of powerful hydro-cannons.
This section needs a rewrite
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 Sahara became a desert. The Missing Kingdom has reportedly to have completely disappeared, leading it to be 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 an recording device and left clues to his whereabouts for future generations to find.
During his return to Earth, Steppenwolf invaded the kingdom of Atlantis 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 Atlantean Royal Guard. Despite their attempts to combat his invasion, Steppenwolf successfully retrieved the Mother Box, escaping through a portal.
- Due to the events of Man of Steel, it is implied that Atlantis was heavily damaged from the attempted terraforming by the Kryptonian World Engine.