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Hundreds of miles below the sea surface near Japan’s coast lie vast fields of yellow flowers. These flowers, however, are not traditional plants but rather crinoids – sea creatures related to starfish and sea urchins. They use their frond-like arms to filter plankton for food while anchored to the deep seabed.

The cliche that we know more about the surface of the moon than about our own oceans is given vivid new currency in this blend of natural history, popular science, travelogue and ecocriticism by the Australian novelist and poet James Bradley. The book takes us from pole to pole and surface to bottom of the blue realm that covers most of Earth.

The majority of the Earth’s living space, inhabited by intelligent species like whales, dolphins, and octopuses, renders our land-based civilizations and environments insignificant. Features like forests, mountains, rivers, and weather hold little importance in their world. Instead, they have their own unique equivalents, such as the crinoid meadows, underwater peaks and valleys, and ocean currents that transport large amounts of warmth and nutrients globally. Even gravity has little impact for creatures who live indefinitely in the depths of the ocean, and there are species that live in areas without sunlight.

Our understanding of the extent of evolution’s creativity is limited while our knowledge about the oceans is lacking. Only through exploring the oceans can we encounter organisms similar to the very first animals to exist. Sponges, comb jellies, and cnidarians (such as jellyfish) provide insight into the earliest multicellular life forms from over 540 million years ago prior to the Cambrian explosion. The Portuguese Man o’ War is not actually a jellyfish, but rather a colony of minuscule creatures called zooids. Corals are a prime example of symbiosis, as they coexist with photosynthesizing microorganisms. In the vast abyssal plains beneath the Pacific Ocean, solitary sea anemones can be found, living a hundred miles from their nearest neighbor. The viability of such a scattered population remains a puzzling concept.

The Antarctic krill, a small crustacean, holds the title of being the most abundant wild animal on Earth, with a total weight of several hundred million tonnes. It plays a crucial role in supporting the ecosystems that sustain penguins, seals, and whales. Despite this, we are still unaware of its migration patterns during the winter months when sea ice expands. On the opposite end, we have the magnificent whales, capable of communicating through sound over vast distances – a feat that has been affected by human marine activities that have added noise to their environment.

Bradley effectively illustrates the immense magnitude of the deep oceans, both in size and duration. They make up the largest environment on Earth, accounting for roughly 90% of habitable space and harboring 95% of all life. The deepest part is the Mariana Trench, located in the western Pacific where two tectonic plates meet and reaching a depth of nearly 11km. The extreme pressures at these depths make exploration difficult and potentially dangerous for humans.

Despite their extreme depth, these deep abysses contain oases of diverse life forms that cannot be reached by light. These communities are found around hydrothermal vents, which were first discovered in the 1970s by submersible missions. These vents, located over volcanic fissures, provide heat and nutrients for organisms such as tube worms to thrive. It is believed that life on Earth originated here, protected from the harsh conditions on the planet’s surface, long before any organisms were able to utilize solar energy.

Developed for terrestrial life, we are still reliant on the sea. According to Bradley, more than three billion individuals rely on the ocean for sustenance. This dependence leads to numerous issues for both humanity and marine ecosystems. Reading Deep Water can be distressing as each account of a marvel is followed by a portrayal of how we are harming it. The book opens with a enchanting depiction of bioluminescence – foaming waves emitting pale blue light onto an Australian shore at night, courtesy of tiny organisms known as noctiluca that glow when compressed by fluid movement. However, this scene serves as a cautionary tale about how ocean warming has caused an increase in bloom in areas where they did not previously occur, resulting in toxic “red tides” that turn the water the color of rust and harm marine life.

The ability to navigate the ocean allowed us to gain knowledge about the vastness and variety of our world, but this journey was also accompanied by exploitation of both people and resources. Our networks of trade now heavily rely on goods transported by sea, resulting in almost 3% of the world’s greenhouse gas emissions. One of the most heart-wrenching sections of the book discusses the devastating impact of plastic pollution on the secluded Cocos Islands. This is just the most recent occurrence in the troubled past of these atolls in the Indian Ocean, which were once visited and admired by Charles Darwin, but controlled as a feudal colony by descendants of a Scottish merchant until the 1970s.

The level of destruction and violence happening at sea is astounding. There are significantly fewer fish now than there were one hundred years ago, and conditions on certain ships are comparable to the slavery and piracy that occurred centuries ago. In fact, modern-day slavery and human trafficking are prevalent in some segments of the global fishing industry due to declining fish stocks, causing desperate actions to be taken. The current rate of increase in global average temperature, while concerning, masks the even more dire situation at the polar regions. This increases the likelihood of an Antarctic or Greenland ice sheet collapse, which would have catastrophic consequences. Human-caused ocean warming is having a devastating effect on coral reefs, potentially leading to a mass extinction. As one researcher warns, “coral reefs are always the first to go” in previous mass extinctions, followed by everything else.

Bradley is in search of signs of optimism, speaking with a variety of professionals including engineers, conservationists, scientists, and activists who are searching for solutions to reverse harmful patterns. Some are working on alternative fuels for ship transportation, while others are promoting a return to wind-powered vessels with the use of advanced ships and “Flettner rotors”. Marine biologists are also striving to identify or produce coral species that can withstand high temperatures and help revive damaged reefs. However, the magnitude of these obstacles can feel insurmountable and genuine efforts can be perceived as insincere publicity stunts. “Fossil fuel companies welcome coral reef restoration,” one researcher explains, “because they can utilize it for their environmental image.”

Bradley states that we are currently in a time of crisis that will last beyond his lifetime. He believes that the enormity of the situation is hard to grasp, but suggests that thinking about the ocean can help us understand. The ocean not only shows us the threats we face, but also reminds us that our world is still full of wonder and beauty. Deep Water, along with two other excellent books, Blue Machine by Helen Czerski and The High Seas by Olive Heffernan, highlights the importance of cherishing our ocean while also bringing attention to the dangers caused by our own selfishness and lack of knowledge.

Source: theguardian.com