There may be a layer of liquid water deep inside Triton, forming a subterranean ocean.

They eventually encounter a subterranean ocean, and make a raft from the stems of giant mushrooms to cross it.

A stream from underground (a subterranean ocean of fresh water?)

I then recollected that the Professor, before our departure, had estimated the length of this subterranean ocean as at most about thirty leagues.

The heat may even be sufficient to maintain a "subterranean ocean" similar to that which is hypothesized to exist underneath the surface of Europa.

The explorers eventually come upon a subterranean ocean.

In a short afterword, Baxter claims to have based his work on a hypothesis related to possible subterranean oceans within the Earth's mantle.

Perhaps the most longed-for possibility is the discovery of subterranean oceans on that shiny, cracked moon.

As he descended through the subterranean ocean, the water around him gradually became clearer.

In June 2009, evidence was put forward for salty subterranean oceans.