The old expression about “sailing off the edge of the Earth” originated from the fact that sailors were heavily dependent on the North Star to navigate. When they sailed far south, the North Star approached, and finally disappeared below, the horizon. They had “sailed over the edge”.
That sounds spurious because sailors were travelling well down south along the African coast. It was when they were travelling West that they had no landfall and many of them never returned.
There was evidence the Phoenicians returned from American lands but their dominance of the Mediterranean was short-lived and they didn’t have good enough navigation tools to land in the same place twice.