Forum From the Archives: 'The Underworld' Illuminates Marvels of Deep Sea

The deep sea is nature’s motherboard, according to author and aquatic explorer Susan Casey. It absorbs heat, buffers excess carbon, drives our climate and regulates the earth’s geochemistry. It’s also home to mountains taller than the Swiss Alps and populated by a cast of “marvelous weirdos:” creatures that have two mouths or three hearts, or transparent heads or eyes in the middle of their backs. And it’s almost completely unknown to us: 80% of the sea floor has never been mapped in any detail. Casey joins us to talk about some of the wonders of the deep sea – and the ecological threats it faces. Her book is “The Underworld: Journeys to the Depths of the Ocean.”