Book excerpt: In this masterful account in the spirit of Bill Bryson and Ian Frazier, a longtime deep-sea diver masterfully weaves together the science and history of Earth's last remaining frontier: the sea. In an age of unprecedented exploration and innovation, our oceans remain largely unknown, and endlessly fascinating: full of mystery, danger, beauty, and inspiration. In Oceans Deep celebrates the daring pioneers who tested the limits of what the human body can endure under water: free divers able to reach 300 feet on a single breath; engineers and scientists who uncovered the secrets of decompression; teenagers who built their own diving gear from discarded boilers and garden hoses in the 1930s; saturation divers who lived under water for weeks at a time in the 1960s; and the trailblazing men who voluntarily breathed experimental gases at pressures sufficient to trigger insanity. Tracing both the little-known history and exciting future of how we travel and study the depths, Streever's captivating journey includes seventeenth-century leather-hulled submarines, their nuclear-powered descendants, a workshop where luxury submersibles are built for billionaire clients, and robots capable of roving unsupervised between continents, revolutionizing access to the ocean. In this far-flung trip to the wild, night-dark place of shipwrecks, trapped submariners, oil wells, innovative technologies, and people willing to risk their lives while challenging the deep, we discover all the adventures our seas have to offer -- and why they are in such dire need of conservation.