The Brilliant Abyss

Exploring the Majestic Hidden Life of the Deep Ocean and the Looming Threat That Imperils It

By Helen Scales
The Brilliant Abyss by Helen Scales book cover. The very top is a light blue like the sky, with a sharp transition to a dark blue like the ocean surface, fading slowly to black at the bottom. There is a picture of a translucent squid with its arms splayed out under the title and subtitle in white caps text.
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The scope of The Brilliant Abyss is impressive, rivaling that of the deep sea itself. Helen Scales covers the deep from a variety of angles: biology, history, geology, medicine, carbon capture, exploration, mining, plastic, and conservation. I’m sure she gets this a lot, but Scales is a great name for a marine biologist and ocean-focused writer. And she is a good one. This paragraph demonstrates how she perfectly captures the duality of the deep sea as being inextricably tied to all life on Earth, and yet so foreign to us:

As soon as you stop thinking about it, the deep can so easily vanish out of mind — more so that that other great distant realm, outer space. The deep has no stars at night to remind us it is there, and no moon shining down. And yet, this hidden place reaches into our daily lives and makes vital things happen without our knowing. The deep, quite simply, makes this planet habitable.

Main Points

Our Relationship with The Brilliant Abyss

Helen Scales starts us out by framing the importance of deep sea ecosystems, giving us important context for the rest of the book.

Invisible connections lead far and wide from the deep sea, keeping balance in the atmosphere and climate, storing away and pouring out vital substances, all processes without which life on Earth would become unbearable or impossible.

With its value established, part of the purpose of The Brilliant Abyss is to ponder our relationship with the deep sea moving forward. I love her perspective on the future, which is optimistic and values-focused:

We now face the possibility of forging a new relationship with the living planet, and we have the chance to decide there are things we just don’t need and places that are special, unique, and important enough to leave alone—and one of those places is the deep.


The deep sea is difficult to study, because it is so inaccessible to us. It has taken lots of innovation and technological invention to get where we are today, and there is so much left to know. Where this book excels is in collecting and curating fascinating anecdotes of how scientists have had to get creative in order to study the deep.

One of those anecdotes is from a team of deep sea biologists, who wanted to study scavengers and how fallen carcasses are broken down. To do this, they dropped dead alligators to the seafloor. Yes, alligators. There are so many of them in Louisiana that they are (humanely) culled to keep their populations under control. And you might as well use them for science!

They returned to these alligator carcasses periodically to study how quickly they were broken down and what kind of life was on them. There’s an amazing photo in the book of a dead alligator covered in about a dozen giant isopods (like a big underwater roly-poly). And one of the carcasses mysteriously disappeared, with evidence left suggesting it could have been stolen by a giant squid!


Scales’ ability to describe what the deep seafloor looks like blew me away. At first glance, the abyssal plains may seem just like vast stretches of boringness; why would you even pay attention to them? But when she describes them as extensive prairies dwarfing the Eurasian Steppe, and consisting of SIX VERTICAL MILES of mud piled on top of the actual rocky seafloor, you can’t help but feel awe at their extent, and disbelief at your previous ignorance of them.

I had never really thought before about how scientists find seamounts. I guess I just figured they bumped into them, or had general ideas of where they were from seafloor mapping. But Scales set me straight— did you know that seamounts are so big and dense they have a gravitational pull on the water around them? This effect creates “piles” of seawater over the seamounts that satellites can detect as bulges on the ocean surface. Amazing!

Emerging Benefits and Threats

While harvesting creatures from the deep is too difficult and expensive to sustain an extractive industry, novel chemicals found there can inspire artificial synthesis of medicines. Scientists can study the unique chemistry in the deep to find solutions to problems we may not even realize exist yet.

On a planet covered with humans, no ecosystem is safe from our impacts. I knew the Deepwater Horizon spill was bad, but Scales enlightened me to new levels of compounding effects the spill has had on the deep. Not only did chemical dispersants injected into the wellhead to “clean up” the spill turn out to be more toxic to deepwater corals than the oil itself, but they boosted bacterial decomposition, draining the water of oxygen and suffocating all life in the area.

What Comes Next?

Helen Scales concludes our exploration of The Brilliant Abyss with a beautiful call to action:

The deep sea will never run out of things for us to dream about. Places will remain unseen and unvisited, fleeting moments will be missed, and nimble creatures, whose existence nobody can guess, will keep slipping out of sight. We need to do all we can to keep it that way.


The deep sea is still such a foreign ecosystem to us. We’re learning more about it all the time, and it has yet to cease to surprise us. It deserves to be conserved for many reasons:

  • carbon storage
  • nutrient recycling
  • pharmaceutical development
  • unique species
  • more we have yet to discover

I encourage you to read this book yourself for many more facts and stories I did not include here. The deep sea continues to mystify and intrigue us, and there is so much left to learn.

Want to read more? Find The Brilliant Abyss here: Bookshop

The quotes above were gathered using Readwise. It’s a truly amazing app to help you remember what you read. If you want to try it out, use my link and we both get a free month 🙂

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