subsurface

[ suhb-sur-fuh s, suhb-sur- ]

/ sʌbˈsɜr fəs, ˈsʌbˌsɜr- /

below the surface, especially of a body of water.

Origin of subsurface

First recorded in 1770–80; sub- + surface

Broad completely misses the point that sub-surface demolition makes plugging the well “from the top” unnecessary.

The Case for Blowing Up the Oil Well |Christopher Brownfield |June 5, 2010 |DAILY BEAST
Both surface and sub-surface storage sometimes hold the water from the streams at times when it might be advantageously used.

The Economic Aspect of Geology |C. K. Leith
The sub-surface structure, even though complex, can be readily read from one of these surface maps.

The Economic Aspect of Geology |C. K. Leith
The only safe thing appears to be the sub-surface irrigation plan, for which, fortunately, there is plenty of room on our lot.

The House that Jill Built |E. C. Gardner

About three inches below the soft snow was a sub-surface crust strong enough to carry the bodily weight.

My Attainment of the Pole |Frederick A. Cook
In addition, there are indicated the sub-surface contours of one or more of the coal seams which are selected as datum horizons.

The Economic Aspect of Geology |C. K. Leith

sub-surface

the layer just below the surface of water, the earth, etc