(5x09) Pantheon Genesis: Part 3, Episode 3
The Pantheon mourn their leaders' tragic deaths. They turn to the disembodied mind of Oron for guidance, but seeing the tragedy that his last advice has caused, he excuses himself from that role. As they scramble to reorganize their leadership, they discover that an even greater tragedy lay on the horizon, and that their entire little civilization would soon be doomed. Noting a gradual trend of sea level rise, and plotting its curve, they inferred that the world was beginning to undergo a warmer climatic period, with glaciers melting into and increasing the size of the oceans at an accelerating rate. That would, within a generation, flood not only their entire build site, not only all of the coasts of Auei on which their civilization was based, but nearly the entirety of Auei proper itself, consisting almost entirely of lowlands except some high mountains in the far south.
Redirecting their civilization's efforts to instead trying to preserve themselves, they tried at first to have everyone move everything further inland by foot, but it became clear very quickly that there wasn't going to be time for that, and it was not clear how far inland would even be far enough by the time the waters had stopped rising. Having thus far only small long-range exploratory boats and large short-ranged barges for crossing the narrow passageways between nearby coasts, they directed their civilization to begin building large boats on which many people could survive extended journeys far out at sea with enough supplies to begin rebuilding wherever they should land.
Two prototype ships were built. One of them, constructed under the direct supervision of the Pantheon themselves as a means of figuring out and teaching the construction techniques, was going to be the Pantheon's own escape ship. The second prototype was going to be for the regent's royal family of demigods. More ships were planned to be built, an entire fleet with which to rescue the whole Aueian civilization and all of their accumulated knowledge, but it turned out even the Pantheon's science was not accurate enough, the sea was rising much faster than even they expected, and it began to inundate the coastal core of the civilization before even the third ship could finish construction.
Apologetically, the Pantheon are forced to abandon the civilization that they had sought to elevate, as it was subsumed in the floodwaters of the rising sea. They directed their regents to direct the people generally to head inland up hill, carrying with them anything that they could while keeping ahead of the waters but leaving anything unnecessary behind in order to save themselves — though the Pantheon and their regents knew and feared, with the geography of Auei, most of the people would not be able to run far enough fast enough to escape the floodwaters for long enough. The Pantheon themselves and then their regents' family then retreated to their separate ships, there to sail away to safety.
The regents' ship followed the Pantheon's ship southward, chasing the receding shoreline as almost all of Auei was swallowed up before them, expecting to eventually find dry land somewhere before the high mountains of the south. But the warming climate and sudden expanse of new sea before them generated storms unlike any they had built their ships to weather. Combined with the primitive nature of their ships and navigation instruments, the ships were separated and both were blown off course, continuing to sail south in search of land through what was by then the Tasman Sea, only when they began to enter unreasonably cold southern waters realizing that somehow they had either missed Auei (as they had), or worse, that it had been swallowed up entirely.