I love how flerfs think they need to verbosely explain simple concepts like the vanishing point, and completely ignore the fact that we're talking about things being visible behind the horizon.
That's not how perspective works. You don't have stuff beyond the vanishing point.
That is how perspective works.
Below is a model of a barbed wire fence on a flat plane. The fence is repeated every 200 meter for 10km.
After the first 1000 or so meters the fences all start blurring together until 30 fences all appear as a black strip on the horizon. The sharp edges have gone. All we see is a condensed version of the fences.
Same principle happens with water. A curved surface is not required for this optical effect to take place.
If we are standing on the seashore, looking out to sea, the horizon appears to be at eye level. It appears very sharp, because all that we can see is compressed to a sharp angle’
This effect is happening in the picture above with air haze above the shoreline where the land meets the water. As the water gets closer to the shoreline, there is a layer of haze, created by tiny aerosol droplets of seawater that are ejected into the air when waves break and bubbles burst at the ocean surface. Even in a bay, there are small waves that create this effect closer to the shoreline.