An awe-inspiring and panoramic investigation into the hidden world of the deep sea — a mysterious, unforgiving landscape whose secrets radically revise our understanding of life on earth.The deep sea is one of humanity’s last frontiers. For most of our history it has been a remote realm shrouded in obscurity. But here, where the light cannot reach, lies a strange, wonderful and breathtaking portal into Earth’s past, teeming with scientific marvels and lessons for the future of life on this planet.In The Dark Frontier, marine microbiologist and deep-sea explorer Jeffrey Marlow plunges us into the ocean’s depths and invites us to witness close-up encounters with its hidden brilliance. Translucent shrimp dance through sulphureous vents, crabs stretch twelve feet from claw to claw and the eerie chalk-white towers of the ‘Lost City’ loom. Back on land, diplomats and conservationists negotiate the management of the vast open ocean, as human forces threaten ancient underwater ecosystems. Immersive and illuminating, Marlow’s journeys heed warnings too: we are irrevocably changing the deep sea before we have even gotten a chance to know it.This expansive book offers crucial and surprising insights into the twinned forces of exploration and exploitation in the deep sea. It shows how life can thrive in even the most extreme conditions, and how new ways of engaging with the ocean’s depths are revealing critical links between the deep sea and life on land. The Dark Frontier expands our understanding of biological possibilities – and our responsibilities – on Earth and beyond.