
Before Aman was removed from the circles of the world, there was Ekkaia, the Encircling Sea and beyond that, the Void. The whole world was flat and floated on that Outer Ocean, which formed air above sea level.
Now our world is round (accurately: geoid) and that of the Valar can still be the same as it was. As I recall there is no exact information about it.
Belegaer; (Bermuda triangle...)
Wow, Miguel, that is a fascinating detail! Your elaborate answer suggests that your own question was to some extent rhetoricalI am amazed by your insight into the topic!
I share your point, it has to be a hidden half. So ships and airplanes got lost in the Bermuda triangle because that is where the passway to Aman was hidden?