Flood Stories of Euterra

Across the cultures of Euterra, there are 4 (technically 6 if you count the Pa-Nehasi, whose version is identical to the Khemeti version in every way but the names of 2 deities, and the Halflings and Gnomes who differ culturally but have an identical story) who have some form of a flood myth: the Achaians, the Vicini, the Khemetiu, and the Gàidhlig/Gaeilge (Gnomes/Halflings).
The names and exact details vary, but the general story is always the same: there were many people, some great force flooded the world sparing only a select few, and everyone now is descended from them in some way.
Achaian
The main characters in the Achaian version of the flood myth are Prometheus, Deucalion, his wife Pyrrha, and of course Zeus. The Achaian flood myth takes place in the Bronze Age, when humans were tall, mighty, and could live for hundreds of years. Our story begins with Prometheus, a titan who found himself incredibly fond of the humans.
He gave them numerous gifts of knowledge such as: how to count the days, mathematics, writing, how to tame horses and oxen, how to make sails and ships, how to make medicine, and various methods of divination such as extispicy (entrails), ornithomancy (birds), and oneiromancy (dreams).
However, he had one final gift to give them—fire. Prometheus stole fire from the gods themselves and hid it in a fennel stalk to give to the humans. For this crime, Zeus chained Prometheus to a stone high in the Anatellos mountains and sent an eagle to devour his liver every day.
Zeus also wished to destroy the humans for the crime of receiving the stolen knowledge, but the other gods urged him not to. They reminded him that, if the humans were all to die, then there would be no one left to make sacrifices or pray to them. After much deliberation, the king of the gods decided to spare Deucalion and his wife Pyrrha.
Deucalion, the son of Prometheus, was the first human to ever found a city, the first king to rule over men, and the first man to erect temples to the gods.
Zeus instructed Deucalion and his wife Pyrrha to secretly build a great chest and hide inside of it. In some versions of the story, Zeus visited the pair himself to relay these instructions, and in others he visited Deucalion in his dreams.
Once the task was done, Zeus enchanted the chest to be indestructible. Then he flung open the gates of the sky and sent a torrential rain for 9 days and nights to flood the world. Deucalion and Pyrrha hid inside the chest and floated on the waves for 9 days and nights as the human race was swept away by the storms.
On the morning of the 10th day, Deucalion and Pyrrha opened the chest to find the storms had swept them to the top of Mt. Oros. From there they observed the world, and that the humans had been destroyed. But, as a reminder of their crime, Zeus had left half the world underwater. This water became known as the Geocycladic Sea. The rest, Deucalion and Pyrrha named Achaia.
The gods told Deucalion and Pyrrha to recreate the humans by taking the bones of their mother and throwing it behind them as they walked and travelled what remained of the world. Though Deucalion was confused and could not understand, Pyrrha realized that the mother of the prophecy was Gaia, the earth, and her bones were rocks. So, Deucalion and Pyrrha wandered the world, throwing stones behind them as they walked. Those thrown by Deucalion became men, while those thrown by Pyrrha became women.
Vicini
The Vicini version of the flood story is nearly identical to the Achaian one, save for a few key differences. In the VIcini version, the humans saved by Jupiter (the Vicini counterpart to Zeus) were not Deucalion and Pyrrha, but a humble old couple named Baucis and Philemon. Jupiter and Mercury went together to judge the humans but were turned away by everyone except for Baucis and Philemon, who showed them proper hospitality despite their meagre means. Thus, Jupiter decided these two were the only humans who would survive the flood.
The second major difference is that, rather than hide in a box, Jupiter told Baucis and Philemon to build a boat and fill it with as many flowers as they could find which they were to scatter across the waters as they floated. The flowers thrown by Baucis became men, while the flowers thrown by Philemon became women.
The final major difference is that, rather than washing up on a mountain, when the waters receded, Baucis and Philemon found themselves floating in the middle of Lake Divi. The ship they built became the Insula Sanctissima (Most Holy Isle).
The gods asked Baucis and Philemon what they wished as a reward for their faith. The old couple said only that they wished to be together for all eternity, so the gods turned them both into glorious trees with translucent pink leaves that are always in full bloom and never fall. These are the trees which now cover the whole of the Insula Sanctissima.
Khemeti
In the Khemeti version, the sun god Ra observed one day that the humans had grown unfaithful, disrespectful, and arrogant. They failed to give the gods their due sacrifice, and some even outright cursed or insulted the gods openly. This angered Ra, so he sent Sekhmet, the lion-headed goddess of war and destruction, to destroy the human race.
Sekhmet set about her task with terrifying enthusiasm and violence. She killed so many that the blood flowed into the great Iteru River, causing it to turn red with blood and flood the world. Sekhmet drank this greedily, delighting in her work.
The other gods, seeing this, went to Ra and begged him to cease the slaughter. They made him realise that, if all the humans died, there would be no one left to make any sacrifices to the gods. He ordered Sekhmet to stop, but she had lost herself in a battle frenzy and could not be brought so reason.
So Ra made a lake of beer and dyed it red so it looked like blood. When Sekhmet saw the lake, she drank it dry and became very drunk. Where she fell asleep, the land was flattened and became the Koregos Plains (which the Khemetiu call Ahet-Henkyt, “the Bed Fields”). When she woke up covered in red stains from the beer, Ra convinced her that she had indeed finished her task and she calmed down. The now drained lake bed became inundated and is now the Belvi Swamplands (which the Khemetiu call the Ibeh Sh'a, "Swamp Suffused with Blood").
However, as a reminder of the fury of the gods should they ever grow so disrespectful again, Ra left a portion of the world flooded which had once been mountainous. This created the Sekhawy Sea ("Sea of Remembrance"), while the tops of the now submerged mountains became the Heseb Islands ("Broken Islands")
After her rampage, only four tribes of humans remained: the first settled around the Iteru river and became the Khemetiu; the second had fled to the mountain tops, now the Heseb Islands, when the world flooded and became the Panehasiu; the third took to living in the Belvi Swamplands and became the Vicini; the fourth settled in the land where Sekhmet had fallen asleep and became the Achaioi.
Panehasi – As with much of their culture, the Panehasi flood story is identical to the Khemeti story. The only differences in their version are the names of the deities Ra, called Mandulis by the Panehasiu, and Sekhmet, who is called Menhit (a telling name literally meaning “she who massacres”). It is believed that these were once the names of Panehasi deities, now mostly lost and remembered only by their use as alternate names of Khemeti gods.
Gaeilge/Gàidhlig (Gnomes/Halflings)
The Gnomes and Halflings have an identical flood story. The Gaeilge/Gàidhlig story begins with the descent of the Tuatha Dé Sinnsear (“Tribe of Ancestor Gods”) to the mortal world. As their legends tell, the Tuatha Dé Sinnsear were a tribe of gods who grew bored of their lives in the heavens and descended to the mortal world to rule over it as kings.
To this end, the Tuatha Dé Sinnsear made war on the mortals. Though “war” is perhaps not the most accurate term, for none could ever hope to stand against the might of gods. To conquer the world, the Tuatha Dé Sinnsear decided that a single, decisive, and devastating strike was necessary. Thus they planned to flood the entire world, purging it of all the mortal races so they could start anew ruling over what remained.
But the prophetess Ceithlionn of the Tuatha Dé Sinnsear saw their plans and foresaw that the destruction of the mortal races would be disastrous. Without mortals, they would have no one to rule, no one to guide, no one with whom to experience the mortal world and all it has to offer. The Tuatha Dé Sinnsear would be rulers of naught but a lifeless wasteland.
But Ceithlionn knew she could only save a few, or her kinsmen would learn of her plan and strike her down. She chose only a select few: three women (Banba, Fódla and Ériu), and three men (Mac Cuill, Mac Cecht, and Mac Gréine) who would recreate the mortal races. She went to them in the form of an old woman and instructed them to hide in a well. While hiding in this well, they were to eat nothing but a single hazelnut each day for nine days. If they could accomplish this, they would be saved.
The mortals chosen by Ceithlionn were at first wary and unwilling to do such a thing, for they could not imagine the power held by the Tuatha Dé Sinnsear. It was Banba who convinced them through great words that they ought to heed the words of Ceithlionn. They did as they were advised, and in nine days the deluge began. As the mortal races were swept away, the six mortals chosen by Ceithlionn were transformed into salmon. They swam in the waters for nine days.
When the waters receded, the six mortals returned to their original form. In the days that followed, they married and had 15 children. Each of these children would go on to sire one of the mortal races. the 3 races of Daoine (humans), the Leoin/Leòmhann (Leonin), the Eiteach/Itealach (Aarakocra), and so on and so forth.
Though these do not represent all the mortal races, as there are others who are a result of manipulation of one of the original 15 (such as the Aar-mesu or the centaurs, born of humans), or who were created afterwards (such as the satyrs, created by the Achaian god Dionysus).