[Telepathic Intruder]

You have to go something like 20 miles to begin to see earth’s curvature. There’s very little air that high so you’d die without a pressurized cabin or a space suit anyway. There are countless ways to debunk flat earth but no ways to debunk round earth. Occam’s razor.

[USFRIENDINVICTORIA]

I can see the curvature of the Earth, while looking at the ocean from the top of a 200 ft high hill.

[philman_36]

You have to go something like 20 miles to begin to see earth’s curvature.

Really?

http://mathcentral.uregina.ca/QQ/database/QQ.09.02/shirley3.html
This shows that at eye level of 6 ft. the horizon is 3 miles (at sea or on a level plain).

3 miles away to the horizon. Okay. That would mean a roughly 6 foot tall man's head would be even with a roughly 6 foot tall man's feet when standing 3 miles away on a X axis.
Feet-_Head

So when you stand on a beach you should see, according to the mathematics (8 inches per square mile), the curve of the Earth when you pan the horizon.

If you are on the X axis and the Y axis is the horizon there should be a visible curve on the Y axis.

You are seeing more than 3 miles, aren't you?

Pan of horizon from Gillis Beach 10 February 2019
Pan of horizon from Palos Verdes to Santa Monica 7 March 2018 (that's 49 miles, BTW)

Do you see the horizon (the water) curving after 3 miles?