This well researched video, several years coming together, fully debunks every flat earth claim with the fact of the matter:
Earth is a massive sphere with determinate dimensions.
It is not hard to figure out if you are honestly interested in the truth.
Flat Earth might have been a contrarian fun run, a confused state due to all the false information promoted, a dedicated alternative non-objective realm, or a confirmation of one's religious beliefs, but as a movement expecting to prove the outlandish claim that Earth is a flat plane, well, it just ain't gonna happen no matter how hard one believes :)
Hope you enjoy this, the doco maker, Noah, is a friend and correspondent (he's on FB, but not here on Steemit, yet at least!).
As I've researched deeply into this and related geodetic and cosmographic subjects I'm happy to discuss any valid points in an intelligent and non-emotive manner, once you've watched the video!!!
Here is geodetic surveyor of four decades of global experience Jesse Kozlowski's youtube channel, with many demonstrations of measuring the curvature. Jesse is featured in the Noah's video, and is another friend and correspondent.
So we have a deep field of knowledge and research to draw from.
Please also see these related articles of mine, which are the beginning of a much longer series.