Try Iriquois and Papuan.
There is also a turtle involved in a Hind "churning of the sea" myth and soome other turtles in various meso-American tales.
Thanks for the pointers, From many - one. However, I distinctly recall the myth in question has a middle Eastern (Fertile Crescent) origin. Of course, this is from my reading of several decades ago. My memory may be "off"; but this is the sort of story I just "naturally" remember.... Will try to find you a cite.