INVESTING IN DEEP-SEA SUBMERSIBLES. “A new generation of daredevils is seeking to plunge through nearly seven miles of seawater to the bottom of a rocky chasm in the western Pacific that is veiled in perpetual darkness. It is the ocean’s deepest spot. The forbidding place, known as the Challenger Deep, is so far removed from the warming rays of the sun that its temperature hovers near freezing. . . . The rush is happening now in part because of advances in materials, batteries and electronics, which are lowering the cost and raising the capabilities of submersibles. Still, the challenges are formidable.”