Pre-Socratic Greeks, like Xenophanes, lived on the coast and went to sea, but thought the world was flat. https://en.wikipedia.org/wiki/Xenophanes
Until 1600s or so, Chinese people thought the world was flat. https://en.wikipedia.org/wiki/Flat_Earth#East_Asia , even though many Chinese people lived on the coast and sailed the seas.
Pre-Socratic Greeks, like Xenophanes, lived on the coast and went to sea, but thought the world was flat. https://en.wikipedia.org/wiki/Xenophanes
Until 1600s or so, Chinese people thought the world was flat. https://en.wikipedia.org/wiki/Flat_Earth#East_Asia , even though many Chinese people lived on the coast and sailed the seas.