For love of the deep sea

 kw: book reviews, nonfiction, science, oceanography, adventurers, submersibles, memoirs

Spoiler: Susan Casey did indeed get to dive with Victor Vescovo in his ultra-deep-diving submersible Limiting Factor. Here they are about to dive to the base of Loihi, as we Haoles call it. The Hawaiians call the soon-to-be-a-Hawaiian-Island Kamaʻehuakanaloa. More on that anon.

Ms Casey's book is The Underworld: Journeys to the Depths of the Ocean. She has been enthralled by the ocean as far back as she can remember. She recounts her own life briefly, and chronicles the growing knowledge of the deep sea as humans have prepared more and better ways of seeing into it and of going there.

Many may still think of "the abyss" as a near-lifeless volume of water, and of the ocean floor as a vast stretch of "unoccupied" real estate with resources we can harvest with impunity. Their understanding is a few generations out of date. Two striking facts emerge from putting eyes in the deep sea, whether robotic (in remotely-operated vehicles, or ROVs) or in person: Firstly, life is everywhere, right down to the bottom of the deepest trenches; and Secondly, our trash is everywhere, from plastic bags and other litter even in the deepest holes, to fibers and bits of "stuff" in the flesh of fish and other animals captured all up and down the water column.

The book lacks an index, which precludes my going back to find the name of the new species of amphipod (they look vaguely like shrimp without the long carapace) which incorporates plastic fibers into its tissues, because, well, it has to. That's easier than trying to exclude them!

Along the way we learn of fish like bristlemouths (they have lots of sharp, very thin teeth), smaller than a finger, that exist in such numbers that they outweigh the entire mass of all mammals put together. Wouldn't you know it, as soon as they were discovered, fishing businesses began to speculate about how to make a net that trawls deep enough (a few miles), with fine enough mesh, to catch a few trillion of these for, well, whatever use can be found for them. That's ignoring the equivalent trillions of squids and jellyfish and hydrozoans (like chains of jellyfish—some are 150 feet long). This "bycatch", if deemed less valuable than the fishes, will be discarded, dying and dead, by the thousands of tons. I wonder what that will do to the chemical balance of the ocean? Ms Casey writes, "The idea of commercially fishing the twilight zone is off-the-charts stupid. That doesn't mean we won't do it." Lust for money makes people stupid.

We also learn of snailfish, the deepest-dwelling fish so far known. They live as deep as 23,000 feet, or 7,000 m. These snailfish came to bait dropped on the ocean floor.

Pressures of several tons per square inch affect the ways proteins work, and so far, snailfish and a few other fish species have been able to evolve ways to counteract certain pressure effects, but they haven't made it all the way to the bottom of the deepest trenches, which measure about 37,000 ft, or nearly 11,000 m. Other animals have done so, and are seen crawling around in the deepest of deeps.

The author devotes a chapter to the things she learned at a conference about seabed mining, and about efforts to prevent it or delay it. Large areas of the "abyssal plain", the flat-lying areas at depths between three and six kilometers (10,000 to 20,000 feet, or 2-4 miles), are paved with polymetallic nodules. Once called "manganese nodules", they consist of oxides and hydroxides of many metals. The transition metals (Cr, Mn, Fe, Co, Ni, Cu, Zn) are the most abundant, but many other metals are present, including "rare earth" metals, which aren't really rare, but they are rather hard to separate from their ores. At one time they were thought to grow rather quickly. It has been learned that their diameter increases by one or two millimeters per million years.

Polymetallic nodules grow slowly enough that many animals live on and in them. The beautiful sponge in this picture distracts from the numerous "little white things" seen on the nodules. Consider this: every time scientists get the opportunity to sample the seabed, they find that about half of the organisms they bring up have never been seen before. This is also true of samples taken at deep hydrothermal vents, the "black smokers" and scarcer "white smokers". We don't know enough to know what we'd lose if millions of acres of the ocean floor were to be scraped clean, or if thousands of metallic "chimneys" at hydrothermal vents were "mined". We do know that the mid-to-deep creatures are intimately involved in the carbon cycle, which would be dramatically altered, and not for the better, by all the large-scale extraction businesses just mentioned. 

Hey, climate change activists? How come the Cancel Culture hasn't begun to target deep ocean mining firms? Here's where you can have a much greater impact than all prior efforts so far, combined! Get on it, my favorite fanatics!

So far we have just investigated a percent of a percent of a percent of what the ocean contains. Nearly all land life is found within 20 meters of the surface; in tropical rain forests, a decent proportion extends to four times that high, but those account for just a few percent of the total area. The volume of the terrestrial biosphere is thus about 3,000 trillion, or 3 quadrillion, cubic meters. The volume of the ocean is 1.33 million trillion, or 1.33 quintillion, cubic meters: 444 times as much! While it's unlikely that there is 400x as much biomass in the ocean as on land, it is quite reasonable to expect between 10x and 50x. And we don't know what 99.99% of it is!

In her quest to get to know the ocean deeps, naturally Ms Casey was eventually brought into contact with Victor Vescovo, who spent around $40,000,000 to have a full-ocean-depth submersible built, and to obtain ships and other equipment and crew, so he could dive to the deepest point in all five sections of the ocean. I reviewed his book about those experiences a couple of years ago. He has since made more dives in those locations and many more, sometimes solo, and more often with scientists accompanying. His sub Limiting Factor has been purchased by an organization named Inkfish Ocean Exploration (they don't have a website that I can find; it's owned by Gabe Newell). She accompanied a couple of the cruises, and was then asked if she wanted to take a dive herself (Did she ever!).

In 2021 she went on a dive with Vescovo to the base of the Kamaʻehuakanaloa seamount, to retrieve a costly piece of equipment that had descended and failed to ascent...and they had time for some exploration. While this dive wasn't in a trench, it did reach a depth greater than 17,000 feet, or 5 km. At the time, the number of people who had been on dives that deep numbered a couple of dozen. That number is growing, partly from the efforts of Inkfish and even more from manufacturers such as Triton (who manufactured Limiting Factor) that make 5- and 6 km-rated submersibles. Some of these can hold six or more persons. In addition to the immense scientific value of having eyes in situ, the huge impact just being in the deep ocean has on everyone who experiences it is slowly changing the public perception of the deep ocean.

I had an idea. Take every executive from a seabed mining company to see the nodule fields for themselves. I think of it as a kind of intelligence test. If someone takes such a drive and still has only dollar signs in his eyes, take him back down and leave him there (I suspect very few females could be that rapacious).

Failing that, get this book and read it. Read other books about the deep ocean. It's a problem that it costs 1,000 to 100,000 times as much to go one mile down as it does to go one mile up…in many places you can hike a mile up a mountainside in $30 sneakers and wearing jeans and a warm shirt. A tourist ride in a submersible costs in the $50,000 to $500,000 range. A bit more than the typical ocean cruise, and it lasts only a day (plus getting to and from the dive site). And bookmark this NOAA site, which access to livestreams from ships employing deep-diving ROVs to see what's going on, typically about a kilometer deep, but highly variable. During dive season (typically April to November, at least in the northern hemisphere), I like to have one of these cameras going on my screen. In the off-season they have highlights videos available.