Cheryl Morgan just sent me this little gem, for which I owe her.

A seismologist at Washington University in St. Louis has made the first 3-D model of seismic wave damping — diminishing — deep in the Earth's mantle and has revealed the existence of an underground water reservoir at least the volume of the Arctic Ocean. It is the first evidence for water existing in the Earth's deep mantle.

How cool is that?

The question is, will the first to explore this underground sea find the initials of Arne Saknussemm already carved on the shore, waiting for them...