What if it is like the island that Calypso was on in greek mythology, where we have be lost and alone to find it, can’t stay forever, and can never find it a second time. We have already been told to go alone, and if it is in the dark sea we will be lost and may be unable toreturn due to random island generation.
What makes this theory even more interesting to me is that the myth that this island appeared in was the Odyssey.