Each group kept their Mother Box safe, but in the present day, Steppenwolf and his Parademon army will come to Earth looking for them, leaving it to the Justice League to find them first.
Moviegoers will get their first look at the underwater nation in Justice League, appearing while Aquaman himself joins his fellow superheroes on the surface to fight evil.
Aquaman may still be two years away, but the DC Extended Universe will introduce Atlantis a little sooner than that.
As was revealed in today’s huge Justice League news drop, the movie will feature a flashback from thousands of years ago where three Mother Boxes were given the humans, Amazonians and Atlanteans.