We do not see the ocean when we look at the water that blankets more than two thirds of our planet. We only see the entrance to it. Beyond that entrance is a world hostile to humans, yet critical to our survival. Over centuries, they invented wooden diving bells, clumsy diving suits, and unwieldy contraptions in attempts to go deeper and stay longer. Plunging into the narrow trenches between the tectonic plates of the Earth’s crust, they eventually reached the bottom of the ocean. Today, as nations scramble to exploit the resources of the ocean floor, this book recalls a story of human endeavour that took 2,000 years to travel seven miles, then investigates how we will explore the ocean in the future. Meticulously researched and drawing extensively on unpublished sources and personal interviews, this is the untold story of the pioneers who had the right stuff, but were forgotten because they went in the wrong direction.