What is the dividing line between the sky and the sea?

The line where the sky meets the sea is usually called the horizon.

Horizon is an astronomical term, which is usually defined as the place where the earth's surface is closest to the skyline (that is, the place where the sky meets the earth's surface). On the earth, due to the influence of the curvature of the earth, the horizon is not a straight line parallel to the ground, but a slightly curved arc. The sky above the horizon is the sky we see, and below the horizon is the surface of the earth.

In painting and photography, the horizon is usually used as a sign of picture segmentation to separate the sky from the ground. At the same time, because it has the function of balancing pictures, it is often used in landscape paintings and photos.