subsurface

adjectives

beneath the surface
"subsurface materials of the moon"
subsurface
antonym
overhead
antonym
surface
is similar to
under the level of the ground
"belowground storage areas"; "underground caverns"
belowground, underground
is similar to
beneath the surface of the sea
submarine, undersea
is similar to
beneath the surface of the water
"submerged rocks"
submerged, submersed, underwater
is similar to
being or operating under the surface of the earth
"subterranean passages"; "a subsurface flow of water"
subterranean, subterraneous