If there is any doubt in your mind that water is level, please go perform this experiment.
Oh, water is level so the earth must be level! That claim is a joy to debunk! It's just so easy to debunk you might have to make a webpage for debunking frequent claims to put in your sig, just to debunk this claim!
Well, let me debunk this once and for all.
Let's say we have a perfect sphere 200 km in diameter, which doesn't really matter for this argument. If you made the entire surface of this sphere covered with water that goes 1m up, and you circumnavigated this object at a constant relative altitude and speed you would probably see no difference and the water would just look level. Perfectly works even when you change the parameters.