This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

• Lexulous
• Wordscraper
• Wordosaur

adj. Of, relating to, or situated in an area beneath a surface, especially the surface of the earth or of a body of water.

n. Something that is below the layer that is on the surface.

n. A surface which is a submanifold of another surface.

adj. below the surface

Being or occurring below the surface.

n. A three-dimensional continuum in a space of five dimensions.

adj. beneath the surface

"Among their early findings: a surprising amount of water moves rapidly through fractures in subsurface bedrock during high-intensity storms, playing a greater role in raising pore pressure than had been thought and creating "hot spots" that can fail."

submersed    subterranean    subterraneous    underwater    submerged   

seismic    subterranean    uncharted    geologic    gravimetric