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The Deepest Map

The Deepest Map

336 pages
Published:   July 11, 2023
Non-Fiction  /  Nature
Paperback:   9781773102795    $24.95

Longlisted, SWCC Book Award (General Category)
A Globe and Mail Top 100 Selection

Five oceans cover approximately seventy per cent of the earth, yet we know little of what lies beneath them. Now, the race is on to completely map the oceans’ floor. Scientists, investors, militaries, and private explorers are competing in this epic venture to obtain an accurate reading of this vast terrain and understand its contours and environment.

In The Deepest Map, Laura Trethewey chronicles this race to the bottom. Following global efforts around the world, she documents Inuit-led crowdsourced mapping in the Arctic as climate change alters the landscape, a Texas millionaire’s efforts to become the first man to dive to the deepest point in each ocean, and the increasingly fraught question of whether and how to mine the deep sea.

A true tale of science, nature, technology, and extreme outdoor adventure, The Deepest Map both illuminates why we love — and fear — the earth’s final frontier and contributes to increasingly urgent conversations about climate change.
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Laura Trethewey is an author and ocean journalist whose writing has appeared in the Guardian, the Atlantic, and the Walrus. Her first book, The Imperilled Ocean, was a Globe and Mail Top 100 Selection. In The Deepest Map, she continues to explore the mysteries of the oceans and their watery depths.


A Globe and Mail Top 100 Selection
Longlisted: SWCC Book Award (General Category)


“Picture a 3D jigsaw puzzle being assembled by a thousand fingers over almost as many years; slowly at first, then with terrible speed, a portrait of buried treasures and conflicting ambitions comes into sparkling view. That's what Trethewey has surfaced: the deepest map on earth, being drawn before our eyes.” — Arno Kopecky, author of The Environmentalist’s Dilemma

“I came away from The Deepest Map with a whole new perspective on Earth's oceans. Laura Trethewey's adventurous new book introduces us to the deeply dedicated people (across industries, and all with varied motives) that are working to map the seabed floor. As Trethewey notes early on, “a map is not a neutral tool,” and her deep reporting makes clear the very human process of mapping the world’s last untouched ecosystem. Filled with fascinating science reporting, The Deepest Map is also an immersive investigation into a place where no human has been, but which could find itself imperilled in the future.” — Lyndsie Bourgon, author of Tree Thieves

“A riveting ocean of a book: packed with gripping adventures, high-stakes exploration, and political intrigue. Trethewey leads us to the bottom of the sea and deftly shows why it all matters so much.” — Helen Scales, author of The Brilliant Abyss

“Wow, what a great adventure story. Shipwrecks, octopus gardens, coral reefs as tall as the Empire State Building, 11,000 year-old sponges, deep sea robots — it’s a trip to another world, right here on Earth. This is not just a book about the epic quest to map the ocean floor, but an exploration of the mysteries and life of a planet we hardly know. The Deepest Map is one of those rare books that will change the way you see our world.” — Jeff Goodell, author of The Water Will Come

“Essential reading for environmentalists, armchair adventure divers, and those who care about the world’s oceans.” — Kirkus

“The shape of the book, and Trethewey’s character-focused approach, results in a powerful, almost thrilling reading experience despite the complexity of its scientific material.” — Toronto Star

“A gripping and all-too-timely account of what in more ways than one is turning out to be a very costly and questionably necessary race to the bottom.” — New York Times

“Packed full of interesting information, Trethewey’s The Deepest Map sheds light on the debate over the future of our deep ocean landscape.” — Winnipeg Free Press

“Laura Trethewey’s thorough accounting of our knowledge of and relationship to this ‘last truly mysterious place on Earth’ can only help us along the right path.” — Atlantic Books Today

“Trethewey is a nuanced writer who writes fine-art-level sketches of the dramas and encounters as they unfold. She also has the strong journalist’s knack of cajoling her cast of characters to talk about the magical world they’re trying to chart, so this is a book not just about mapping the seafloor, but also the everyday lives of those who seek it out — the nuts and bolts of how mapping is made to happen.” — Geographical

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