Is the notion that our planet’s roundness a massive conspiracy perpetrated across centuries? The fascinating Flat Earth Society says yes, and attempts to address all of your doubts in their comprehensive FAQ guide:
The evidence for a flat earth is derived from many different facets of science and philosophy. The simplest is by relying on ones own senses to discern the true nature of the world around us. The world looks flat, the bottoms of clouds are flat, the movement of the sun; these are all examples of your senses telling you that we do not live on a spherical heliocentric world
Perhaps the best example of flat earth proof is the Bedford Level Experiment. In short, this was an experiment preformed many times on a six-mile stretch of water that proved the surface of the water to be flat. It did not conform to the curvature of the earth that round earth proponents teach.