The Sea of Lyrielle is a relatively new structure in the landscape of Ga'leah. It did not exist until the Oceans were attacked, and fell to the, the Blight. Now, it is a safehaven to the only creatures of the sea that could be saved from the onset of the Black Water.
As the realization that defeat was imminent finally settled upon Lyrielle the Coming Tide, she became determined to do what she could to save the seas from complete annihilation. After seeing to it that Treasure Island would remain safe for the Pirate Kingdom, Lyrielle transformed her body into the Sea of Lyrielle.
This saltwater structure was large enough to contain the entirety of the Merkind captial, Mahrielle, with a plenty of room to spare. The city rests upon a rocky outcropping in the exact center of the sea. At the border of the city, the outcropping drops severely. The true depth of the the rest of the sea is unknown, but besides short but shallow beaches on the shores of the Sea, the structure itself appears to be impossibly deep with a complicated structure of sea caves extending beneath the surface of Ga'leah but never joining with the now Blighted Maritanis. Besides housing the Merkind capital, the Sea is home to all of the aquatic life that Lyrielle could salvage in hopes that one day the Merkind would and the creatures of the sea would one day be able to return to the Maritanis.
The Sea was created on the outskirts of Caerleon due to the deal struck by the High Queen, Gwenhwyfar Pendragon, and King Triton of the Merkind. Both rulers formed a groundbreaking truce to help each other in the midst of the catastrophe that was the Blight. Lyrielle hoped that the Pendragons would honor this agreement even after the Oceans were lost and help the Merkind to fight to save whatever they had left.