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‘The Underworld’ by Susan Casey

The plight of the Titan submersible dominated the attention of every major news outlet in June 2023, as millions of people followed its disappearance and the eventual news of the implosion that killed all five passengers. What began as a tourist voyage to the wreckage of the Titanic ended in the worst possible outcome.

The tragedy evoked a range of public sentiments, but one commonly expressed was “Why?” Why would you squeeze into a claustrophobia-inducing tube for hours? Why would you descend more than two miles into the pitch-black waters of the ocean to see a shipwreck? Why would you put your life in danger for this experience?

The Underworld: Journeys to the Depths of the Ocean illuminates the world of deep-sea exploration. With her fourth ocean-centered book, writer and editor Susan Casey has established herself as an environmental advocate, adventurer, and lover of all things marine.

Casey defends the premise that there’s value in exploring the dark depths of the ocean. Her justification for the book’s focus is stated early: “The deep isn’t merely a part of our planet—it is our planet. You’d think we would want to be more familiar with it” (5).

This book illuminates the wonder of the deep ocean. Casey weaves together the history of submersible diving, descriptions of oceanic features, and her own experiences with the deep into one simple explanation for continued exploration: Because we must.

The Underworld: Journeys to the Depths of the Ocean

Susan Casey

The Underworld: Journeys to the Depths of the Ocean

Susan Casey

Doubleday. 352 pp.

For all of human history, the deep ocean has been a source of wonder and terror, an unknown realm that evoked a singular, compelling question: What’s down there? Unable to answer this for centuries, people believed the deep was a sinister realm of fiendish creatures and deadly peril. But now, cutting-edge technologies allow scientists and explorers to dive miles beneath the surface, and we are beginning to understand this strange and exotic underworld. The Underworld is Susan Casey’s most beautiful and thrilling book yet, a gorgeous evocation of the natural world and a powerful call to arms.

Doubleday. 352 pp.

Ecological Value

The Underworld focuses much attention on the environmental benefits the deep ocean provides, such as “cycling nutrients, anchoring the food chain, sequestering carbon, keeping the earth’s geochemistry in balance,” and so on (243). These benefits often go unnoticed in our lives of blissful ignorance. However, a healthy deep-sea ecosystem is crucial to the planet and our own well-being. Deep-sea exploration and research are vital to monitoring this health.

Casey bemoans the human practices that disrupt these benefits, such as deep-sea mining and fisheries. When carried out carelessly, these industries remove important pieces of the ecosystem and destroy the delicate balance of the deep. The desire for immediate financial gain often overrides the protection of ecosystem services. People who won’t directly bear the costs make decisions with potentially long-term consequences. Based on her descriptions of these endeavors, she appears to view the deep ocean as off-limits to these industries.

Though her preservationist bias is clear on these matters, Casey has a point. The known environmental value of the deep ocean is immense, and science still has plenty to discover about its nature. Humans do tend to prioritize perceived comfort or immediate financial gain over ecosystem services, ignoring that climate stability, nutrient availability, and the like are valuable.

Stewardship of the environment requires rethinking ecological value in terms of natural resource sustainability.

Aesthetic Value

Casey’s second argument for deep-sea exploration hinges on the beauty found at extreme depth. She details the lights, colors, shapes, and sizes observed in the deep ocean and devotes pages to descriptions of strange fishes, bioluminescent invertebrates, smoking volcanoes, and enormous geological formations discovered through research dives. By her accounts, the aliens we desperately search for in outer space are inhabiting our own oceans.

The aesthetic argument for studying and protecting nature isn’t a new one. Aldo Leopold’s succinct summary of environmental ethics is famous within conservation circles: “A thing is right when it tends to preserve the integrity, stability and beauty of the biotic community. It is wrong when it tends otherwise.”

The visual awe of nature is valuable in itself and should be protected.

In other words, the visual awe of nature is valuable in itself and should be protected. National parks, nature preserves, and wilderness areas were established under this principle. Millions of people in the U.S. travel to these areas to see breathtaking sights every year. The deep ocean may still be inaccessible to most people. However, thanks to modern technology, we’re discovering it holds incredible beauty to be appreciated and protected.

Inherent Value

While Casey’s justification for deep-sea exploration is compelling, Christian readers of The Underworld should notice the conspicuous lack of a third value: inherent. The deep ocean is important for what it does and provides, but even more important for whose it is. If we believe the Creator God spoke the world into existence, then even the cold, dark, inhospitable ocean waters found miles below the surface are his.

If we believe that the Creator God spoke the world into existence, then even the cold, dark, inhospitable ocean waters found miles below the surface are his.

This is an important distinction because it removes human partiality. If the ocean were only valuable due to the services it provides us or the beauty we find in it, then its value could decrease as these are diminished. Repeatedly in the first chapters of Genesis, God states that creation is “good” or “very good.” God is not enhancing the goodness of creation by his words. Rather, he is recognizing the inherent goodness of what he created. Creation’s inherent value doesn’t depend on our subjective opinions about it.

The inherent value of the ocean then flows directly into stewardship. Humans have been given dominion over the created world (Gen. 1:28) but are also tasked by God with protecting it (2:15). As responsible stewards of God’s world, we must oversee oceanic resources and services in a manner beneficial not just to our own species but to all of creation.

The Underworld provides readers with an exciting glimpse into the world of deep-sea exploration and the wonders of the deep ocean. For believers, these discoveries serve as more than just extra information about our world. They remind us of our role as stewards and deepen our admiration for the God who designed every intimate detail of creation.

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