Atlantis is an undersea civilization on Earth.
At some point in Atlantean history, it was populated by 6-inch tall people who used Gold Flying Saucers to explore space. This branch of Atlantean civilization seems to have died out. ("The Secret of the Space Souvenirs")
Atlantis was originally populated by humans (or near-humans). When the city sank beneath the waves, one of the greatest scientists constructed a dome over the city to protect the people. ("The Girl in Superman's Past!")
One day, Nar Lemaris found a way to convert the people to a race of Merpeople, allowing them to live underwater. He then instructed them to smash the dome. ("The Girl in Superman's Past!", "Supergirl's First Romance!")
At some point in Atlantis' history, the Atlanteans built terrible weapons for warfare, including Freeze Rays and Hypno-Robots, among others. They later banned the weapons and left them in an underground crypt. ("Supergirl's First Romance!")
Superman first found out about the Merpeople of Atlantis when he fell in love with Lori Lemaris during his college years. He later told Supergirl what he knows about Atlantis. ("The Girl in Superman's Past", "Supergirl's First Romance!")
Supergirl first visited Atlantis in 1960, when she saved the city from some ancient weapons which had accidentally been freed from a crypt and reactivated. She was then given a tour of Atlantis by Jerro. ("Supergirl's First Romance!")
Peoples of Atlantis
Different sources have shown at least three different races inhabiting Atlantis.
- A tiny race, alienesque but humanoid in shape, and only six inches tall. They used Gold Flying Saucers to explore space. This race has apparently died out, though their fate is unknown. Also unknown is why the contemporary Atlantean races never mention them. ("The Secret of the Space Souvenirs")
- A race of Merpeople. They are telepathic; descended from a Human race, but genetically manipulated to be able to survive in Atlantis prior to its destruction. Able to communicate with marine life. ("The Girl in Superman's Past!")
- A race of Humanoids; possibly the same race as the Merpeople. Also telepathic and able to communicate with Marine life.