The surface of the ancient pond was covered with brown mudThe surface of the ancient pond was covered with brown mud
A satellite above the surface of a celestial body. view from spaceA satellite above the surface of a celestial body. View from space
The sun appeared over the mountain, in front of which the water surface stretchedThe sun appeared over the mountain, in front of which the water surface stretched
В математике: граница, отделяющая геометрическое тело от внешнего пространства. Наружная сторона чего-н..