If you go to the beach and look at the ocean, you can see the curvature with your own eyes.
Of course if you live under a rock and will not travel, enlightenment is not possible
Then it should be easily verified. I'll show you a flat horizon and you show me a curved one.

How far away is the sun here? How can the reflection reach the beach over a curve?
Just something to think about.
Of course if you live under a rock and will not travel, enlightenment is not possible
What a pathetic attempt at a dig. I was in the Navy. I've traveled across oceans to a over dozen foreign lands.
EPIC FAIL on your part.
Oops...to over a dozen...
In 3 miles the curvature is calculated to be about 6'. So from the center of that picture, left to right, there should be 6' of drop on EACH side of center growing exponentially the further away from the center.