An astronaut on the surface of the moon with a us flagAn astronaut on the surface of the moon with a US flag
Boats on the sea surface in the light of the setting sunBoats on the sea surface in the light of the setting sun
Reflection in the water surface of trees and mountainsReflection in the water surface of trees and mountains
Autumn trees on the background of the river surfaceAutumn trees on the background of the river surface
В математике: граница, отделяющая геометрическое тело от внешнего пространства. Наружная сторона чего-н..