The kingdom of Salineas is ruled by Mermista. Its most prominent feature is the Sea Gate, which guards the front of Salineas and protects its inhabitants. The runestone of Salineas is named The Pearl, and the palace has come to be known as the Salineas Castle, both of which Mermista owns.
In Season Four, Salineas was overrun and occupied by the Horde, but Mermista vowed to liberate her kingdom. At the end of Season Five when Horde Prime was defeated, it is assumed that Mermista was able to regain control of her kingdom.
Salineas is a sea-faring realm with light blue sea-shell shaped buildings. The kingdom appeared to be sparsely populated in Season One, but many of the inhabitants returned after She-Ra repaired the Salineas Sea Gate.
Princess Mermista inherited the throne from her father upon his presumable retirement. When Salineas is introduced in Season One, the Sea Gate's connection to the Pearl runestone has been weakening and the gate is slowly falling apart.
Glimmer convinced Queen Angella to send a delegation to Salineas to recruit Mermista and her kingdom to the Princess Alliance. After arriving there, Adora deduced that the decay was caused by an interruption in the connection between the Sea Gate and The Pearl, Salineas' runestone, by reading First Ones' writing on a mural in the throne room. This was one reason the kingdom was crumbling at that time. Resulting of the instability, people fled and the kingdom was understaffed, leaving Princess Mermista as one of the only citizens. She-Ra used the Sword of Protection to heal the Sea Gate.
At the end of "Mer-Mysteries" it is revealed that the Horde had attacked and conquered Salineas using their overwhelming number of soldiers and Hordak’s new weapon, while Double Trouble was at Bright Moon creating a distraction. The Horde was then able to take control of the oceanic territory. The takeover sent Mermista into a downwards spiral, proving that she cared about her kingdom greatly.
Song of the Sea Witch
Salineas is the setting of the children's book, Song of the Sea Witch.
(as Princess' consort)