Similar to Atlantis, Necrus is a domed city. However, Necrus has a more dimensionally unstable status in the ocean; it can only materialize on the [hysoca; plane for brief periods of time due to an alien satellite that periodically enters Earth's orbit as it moves through the galaxy. The Earth's magnetic field triggers a device built into the satellite that opens up a hole in dimensional space. From this hole, Necrus materializes. The location of Necrus is entirely dependent on the position of the satellite in Earth's orbit at the time the dimensional rift is formed. As the satellite breaks free of Earth's orbit, the dimensional rift loses cohesion, causing Necrus to fade away.
Necrus's society seems to be wholly militaristic and unlike Atlantis, has low tolerance for "land dwellers" to the point of utter hostility. Necrus once attempted to forge an alliance with Atlantis due to their shared affiliation of being in the ocean but later went to war for Atlantis's continued acceptance of surface dwellers residing in the ocean such as Colony Alpha.
In other media
- During the production of Aquaman and the Lost Kingdom, the principal photography began under the working title, "Necrus".