The Cataclysm was an event that occurred in the distant past of Shining Blue in Tales of Legendia. Supposedly, half the planet's land mass sank into the sea. Modern researchers believe that the cataclysm took place several hundred years ago, yet there is no solid evidence such event even occurred.
The Ferines once dominated Shining Blue, worshiping the entity, Nerifes, until the Orerines arrived on a giant, island-like ship named the Legacy. This new race soon created land upon the surface of the world by using the power of Nerifes and Ferines to do so. Because of this, hatred began to grow among the races until it fully escalated into a war. The Orerines won and the Ferines fled aboard the Legacy. By using the Wings of Light onboard the Legacy, they established the Kingdom of Terises. However, after the birth of a new Merines, the Ferines again used the power of the Wings of Light, as well as the Merines's life, to eliminate a large portion of the mainland that was created when the Orerines first arrived. When the Wings of Light activates, it causes the tower where it is located to shine vibrantly. A huge glyph resembling a flower then surrounds the ocean where the Legacy is, and finally, a large tidal wave sinks the glyph area beneath the sea.
During the events of the story, this event is remembered more as a myth than anything else, although the truth of its occurrence is recorded in the four elemental monuments of the Quiet Lands. It is later revealed that the Cataclysm was an effort by the Ferines to restore the planet to its original state, in which Shining Blue was entirely covered in ocean before the arrival of the Orerines.