The welsh legend revolves around Dwyfan and his partner, a dragon-like monster was angered, thrashed around and flooded Briton. Only Dwyfan and his partner survived becoming the Adam and Eve (I think Dafydd is our version of Steve - you'd have to know Little Britain to get that one).
A lake near to were I live is named after the beasty, Lyn yr Afanc, claiming this to be the lake of the legend. Although there are many lakes in Wales named after it.
Apparently the original celtic legend was bastardised by a particular group to conform closer to the bible myth.
ABE: here's an outline...
(Welsh) Also Dwyfan. Dwyvan and his wife, Swyfach, are the heroes of the Welsh flood myth. Together they built an ark, filled it with animals, and survived the great flood caused by Addanc, a lake God/dragon/faery. Though later versions of this myth are distorted in order to make it conform to the Biblical version, the old story shines through and we see that Dwyvan was the personification of the male creative principle which has taken over for the older sacrificed God.
The Welsh deluge legend says that he and his wife were each part of one river which flowed into Bala Lake which was at one time called Lake Dyfrdwy, from the term dyfr-dwyf meaning "water of the divinity".
Edited by melatonin, : No reason given.
Edited by melatonin, : Added stuff and corrected error