1.   Drainage patterns could be discerned, suggesting that, deep beneath the desert surface, there was a large aquifer where water collected from a vast expanse.

2.   Even now, this horrid propensity for human flesh lies not so deep beneath the surface.

3.   The latter craft is to look deep beneath the Martian surface in search of water, which is considered the key ingredient for life.

4.   The vessel could cut journey times and transportation costs by taking short cuts deep beneath the Arctic ice.