Deep-sea volcano holds mysteries

Nearly 50 million sq km of seamounts are refuge for new species

The turquoise waters became darker and darker, and squiggly glow-in-dark marine creatures began to glide past in the inky depths like ghosts.

The three-man submarine went down, down, down into the abyss and drew within sight of something no human had ever laid eyes on: Cook seamount, a 4,000-meter extinct volcano at the bottom of the sea.