It doesn’t. Tides disprove the claim that water stays perfectly level:
If the oceans were level, then they would not be obviously below eye-level at 1200 ft:
We can clearly see curvature in many different shots:
Even the famous “black swan” photograph is not reproducible every time:
Soundly even made an excellent “elevator” video using a drone:
Yeah, the ocean looks flat when standing at the shore. But you shouldn’t always trust your eyes:
That’s a JPG. It is not animated.
Is the squared marked “A” the same shade as the one marked “B”?
Here’s that exact image with the rest cropped out:
You should not automatically trust your eyes. This is why we use math for things that are truly important.
Your mind tries to resolve 2-dimensional patterns into 3-dimensional environments. That’s why the horizontal lines above appear to slope.
After that example, are you CERTAIN that the ocean is not curved? Or is it possible that your eyes aren’t the best way to detect curvature?
Thanks for reading: How does water stay perfectly leveled on the Earth if it is round?, Sorry, my English is bad:)