When the fall of Númenor was foreseen by some of its wiser citizens, a small group decided to flee to the bosom of Uinen, Lady of the Sea. They sorcerously achieved to alter themselves to breath water and established a haven beneath the waters of Belegaer. Enough sightings and rumors of them had come down through the years, to produce legends of a sunken city, Vanwa Atalantë (Q. "The Lost Downfallen"). In reality, they were but a small, dosed, and isolationist community, but some still sought either revenge or forgiveness from the surface world.
They appeared as men, women, and children of dark, stern appearance and great stature with strangely pale complexion, cold skin and constantly radiated the smell of mildew. These Atalantëatani (Ad."Kallabêthim") had pretty much lost their ability to survive on land and in air for longer times, as they easily suffered from dehydration, had little tolerance for warmth and easily risked heat prostration if hiking more than a mile or so on dry land or going for four hours without immersion.They also were used to eat raw flesh ( or rather fish) and did enjoy cooked food very little.
Atalantatani of note
Original form in MERP:Atalantedain
The Atlantadain's compatibility with the canon is questionable at best, as it seems doubtful that a lesser Maie such as Uinen could grant such a wish which, in theory, could alter Illuvatar's great plan.Perhaps it would be more believable or credible to reimagine the Atalantedain as a culture of pre-historic deep-sea divers? Or either credit their water-adapted life to some sort of forgotten experimental númenórean technology (if they had flying ships and cannons, why not some sort of experimental deep-sea ships or suits?) Or maybe even forbidden magical experiments ( if they did black magic necromantic experiments on humans, why not some sort of dabbling with early "genetics", in a Sauronic-Sarumanic sense, with humans and watercreatures or even evil experiments in crossing the bloodlines of merfolk-spirits with men?).
- MERP:Arnor- the Land