How can I begin to relate the emotions I am feeling as I prepare for a dive to the sea floor, 2500 meters (just over a mile and a half) below the surface? I begin with a caveat and an apology: this post is written for myself to memorialize these feelings, and thus, will perhaps ramble in spots and be mind-bogglingly boring for most. It’s a weird sense, knowing that I am preparing for an expedition that will take me to a world most have never seen. A true explorer, one of the closest humans to the center of the Earth (not that it’ll actually be that close) during the time we’ll be under the water. It feels like I’d imagine an astronaut’s mindset just prior to a launch. Knowing in advance that I will be encapsulated in a small vessel, fully dependent on the structural integrity of the walls, isolated except for a single radio connection from the outside world, is equally off-putting and exhilarating. As an oceanographer, such a dive allows me to truly and literally immerse myself in my research. That in itself is awesome, but not the reason behind my excitement. My work to date has focused on the water itself, not the seafloor underlying this swath of ocean. As a human, rather, testing the limits of our capabilities, pushing ourselves farther than we could have envisioned, I am astounded. I remember seeing submersibles exploring shipwrecks on television and in movies (ahem, Titanic), and thinking how unbelievably cool it would be to go to the bottom of the ocean. I remember being fascinated by 20,000 Leagues Under the Sea, perhaps still one of my favorite novels. I especially adored an adaptive parody for children lovingly purchased by my mother, 20,000 Baseball Cards Under the Sea. Now I get to be that explorer. Not looking for the Titanic or exploring Challenger Deep, but investigating perhaps the most amazing ecosystem on the planet.
Hydrothermal vents are primordial systems where life flourishes not due to sunlight but due to chemical energy stored in the unique molecules that exist in abundance as volcanic gases mix into seawater. These organisms, from the bacteria and archaea at the base of the food chain to the tube worms (some longer than I am tall), crabs, and mussels at the top, are all uniquely adapted to living under alien conditions. I am privileged beyond belief to be able to submerse myself first-hand into an environment that seems much more likely to be imagined by Asimov or Wells than one that in fact exists on Earth. I have been warned to pack many layers for my voyage to the deep. It gets cold in the deep ocean, 2ºC ambient temperature causes the inside of the sub to be 6ºC. Given that we’ll be on the seafloor for about 5 hours, odds are we’ll get chilly. But I think that I’ll be so consumed with awe and wonder that I won’t need the wool socks and hat. I guess I’ll know soon.
Coming back to the feeling of being like an astronaut, I’m thinking of the engineering that has gone into ensuring the sub can withstand pressures 250 times that at the surface. The titanium sphere must hold. And all of the systems inside, redundant backup after redundant backup to prepare for every eventuality should an emergency arise. Fitted oxygen masks in case a fire necessitates purging the sub from all air (of course I’ve been reassured this has never happened), carbon dioxide scrubbers to reduce the CO2 concentration inside the sub (I wish the planet had some of these, actually…), and camera after camera. As the novice diver on this trip, my job is really that of videographer and observation logger. I have control over two external cameras to capture the extraordinary world and immortalize my experience for ample reshowings (and unadulterated braggadocio) upon my return home. The cameras are also technically for the scientific record to document how instruments were deployed, where samples were taken, and when activities were conducted. But let’s be honest, if I take a picture of a 6 foot long tube worm or expansive biofilm formation, I will use it for a great many purposes.
Anyway, before I ramble too far down a tangent, I am going to curtail my anticipatory thoughts. My only fear is that my sense of enthusiasm is so great that the experience be a let down. I have specifically avoided looking at too many photos and videos from the previous dives so as to remain ignorant of the magical world into which I am about to descend. I’ll soon find out whether I’m whisked into preternatural delight upon submergence from the surface and into the dark expanse of the deep.
And now for the ludicrous task of distilling my first voyage to the sea floor into a manageable post that captures the wonder of exploring some of the most amazing biological ecosystems, geological structures, and chemical environments on the planet. It is surely impossible to relate the experience properly, and in fact, I’m not entirely sure I can yet comprehend the awesome opportunity I was afforded in being able to transit in a submersible to the bottom of the ocean. Perhaps it is best to not even try and to simply overload the post with image after image, but photos alone cannot convey the feelings of being sent to the bottom of the sea.
The anticipation truly peaked once inside the sub aboard the ship, waiting to be lifted off the vessel and into the sea. As soon as we were dangling in the air, my smile erupted, giddy for what was to come. We waited for a few moments, for the ship’s crew to disentangle us from the lines holding us to Atlantis, and then, with a simple flick of a switch, the air bubble keeping us afloat was purged and we started descending. At first, the portholes only glimpsed what could otherwise have been a pool. Brilliant blue water, clear as can be, that just kept getting darker. Darker and darker the world got as we sank until we reached this ethereal blackness that was entirely alien to a boy who grew up in the suburbs of New York. Then pop! Bioluminescence! The first signs of life deep below the surface. Unknown organisms naturally producing proteins within themselves that emit light, organisms so small that they are invisible except for the tiny photons they produce. And there are tons of them. Flitting around, zigging and zagging as we descend, their movements dictated entirely on the small-scale turbulence of the water as they cannot themselves swim fast enough to escape the flow.
And then, suddenly, blackness. The unique feature of this vent system is that in order to get to it, we must transit vertically through anoxic patches of water devoid of oxygen. These “dead” zones were visible to the naked eye in their absence of light. Possibly the same bioluminescent organisms inhabiting the shallower depths dare not pass through this region. It’s also certainly possible that the organisms are there, but because there is no oxygen, they are in stasis or living off the oxidative power contained within other molecules besides oxygen (namely nitrate). Regardless of reason, the starkness of this void is intense. As soon as we descend far enough and the oxygen begins to creep up again, the bioluminescent light reappears. First, flickers that fool the eye and then suddenly a deluge as the ballet of lights restarts after a 300 meter intermission.
We continue to descend, at about 30 meters per minute, for another hour until we reach the bottom. This alien world hazy at first but then sharpening as the craggy seafloor appears. Flashes of light act as beacons, but these lights are man-made. There’s a blinker attached to an instrument much like the flickering of a bulb on the tip of an airplane’s wing. And suddenly, we stop. We release steel plates that weighted us down, dragging us to the bottom, and now we’re neutrally buoyant, meaning we can move very similarly as one would in space (just at a much much higher viscosity). We use the thrusters to move up and down, left and right, searching for our instruments deposited from the ship the night before and waiting for us in the murky abyss. The bottom is surprisingly turbid to me, as I did not anticipate the quantities of flocculent material being emitted from the vents, visible motes of solid sulfur and suspended bacterial biofilms that have been sloughed off the surfaces they colonized by the active flows providing the chemical energy they need to survive.
We begin to search for the Vent-SID, an instrument developed by some of the scientists aboard the ship that is capable of conducting an incubation directly in these harsh environments at the temperatures and pressures the microbes experience, in an effort to minimize the artificiality of putting microbes in a bottle to see what they do and how fast they do it. The instrument is brilliant, but finicky, as maintaining fully functional electronic and mechanical systems at these pressures and amidst the corrosive power of the elements here is far from straightforward. The instrument, a couple meters tall, suddenly appears ahead of us, ready for us to grapple onto with the sub’s robotic arms and transport to the specific vent of interest, Crab Spa.
Crab Spa is a lively place, chock full of crabs (surprise!) and tubeworms and mussels and fish and the occasional tiny shrimp beating its legs close to the viewport of the sub. Biofilms abound and sulfur particles are emitted with great intensity from this mound that first appeared following an eruption about 10 years ago. It was discovered and named by the very chief scientist of the cruise, Stefan Sievert, who passionately explores this system. We see loads of shimmering water emitted from the crevasse that is the vent, signs that hot vent fluid (at least compared to the 2ºC of the surrounding seawater) is mixing with the surrounding sea. We proceed to position the instrument at the crack, carefully and intently placing the sampling wand that will pump vent fluid into our incubation chamber directly into the flow. The temperature at the tip reads 26ºC, exactly the water we want to capture. Success. The instrument is scheduled to turn on in an hour and begin its sets of incubations to quantify a number of nitrogen and carbon cycling rates and describe the microbial communities responsible for them. And so we move on, to complete the other details of our mission.
The next stop on our agenda is the Bio9 vent and a colony of Riftia. These giant tubeworms are dependent on their microbial symbionts to provide food, and grow in such great abundance and to astounding lengths. They surround themselves with chitin tubes (the same material as crab shells), which they use to hide themselves in if they are disturbed. Watching the worms flick themselves into cover when a fish swims by and then slowly inch themselves back out is wondrous. We were here though for work, to pick up a crab trap deposited a few days prior and deploy a new one. A scientist on the boat studies the crabs and the parasites associated with them, and requires as many samples as she can obtain for her research. The crab trap, however, was more of a fish trap, collecting half a dozen fish and a single crab. Each organism is stark white, selectively evolved to be devoid of pigment, losing color that would be irrelevant in a world that receives no natural light. We further pick up some giant mussels for another scientist, scooping a robotic handful at a time, before moving on to our next stop on this magical journey: another vent, cutely but oddly named Teddy Bear.
Our goal at Teddy Bear was simple: collect as much water as possible so that one of the scientists back on the boat can incubate it to look at how the molecular biology changes with time. We utilize a piston-style sampler called a Major, compressed with a spring that when released allows the chamber to expand and fill with water. They have an elongated metal sampling tube so that they can be positioned precisely to suck in the specific water of choice. We fired 5 Majors here, about one and a half liters each, to bring back to the surface. We move slightly to the Riftia colony close by to collect some of these worms thriving at Teddy Bear. Yet more scientists back shipboard rely on their daily harvest of worms to dissect and characterize. Carefully plucked from their rocky beds, the worms are delicately positioned in the containers secured to the platform attached to the front of the sub so that they will be in good condition upon arrival back at the surface.
At this point, we have completed our mission’s specific objectives, but we have plenty of time to spare, and so we utilize it to check on a few of the colonizers that were deployed throughout the cruise and will be collected during the dive the following day. These colonizers are a mesh stretched across a stout PVC pipe. They collect the biofilm and flocculent material swirling around and allow the microbes to set root and colonize. The first colonizer we seek, deposited in a deep narrow trench on the first dive of the cruise, is unable to be seen. We bopped around for 15 minutes or so, searching everywhere for the small orange beacon floating suspended from the top, but to no avail. Rather than continue cruising in circles, we move on to see the colonizers at two much more distinct sites, and trust that tomorrow’s dive crew will have better luck in finding it.
The second colonizer to check was placed on a giant mound of Alvinella. Dubbed the Wedding Cake, this biological assemblage of a few inch-long polychaete worms is a sight to behold! The scientific name is Alvinella pompejana, named after the submersible Alvin that discovered them in the Pacific in the late 1970s (an earlier incarnation of the sub I am now viewing them from!) and Pompeii, given their extremophile nature residing only at hydrothermal vents. They are feather-shaped, but the bristles are not the worms themselves but rather filaments of bacterial colonies. We also look at the nearby nascent mound, “Cupcake,” a much smaller Alvinella colony that in a few years can reach the same sizable heft as Wedding Cake.
Now we return to Bio9. Easily the most impressive site of the expedition, these black smokers defy gravity. The pillars of sulfur and pyrite, coated in bacterial biofilms, tower tens of meters from the base as billowing black smoke is emitted at temperatures exceeding 300ºC into the deep sea. The alien nature of this world is beyond comprehension. We see the colonizer and it looks good, but truly, the scientific endeavor takes a backseat to the simple astonishment of watching these spindly fingers gushing plumes of buoyant smoke upwards into the ocean. I am glued to the window, anxious as we slowly drift higher and higher in the sub, from the base of the structure to the very tips of the fingers, the newly formed mass that can grow by an inch in a week. Utterly amazing, these smokers far exceeded any of the impressive geological formations I have seen before, from the mountains of Yosemite to the Grand Canyon. Fundamentally different as well, the smokers reflect the turbulent and active nature, formed not over eons as the Colorado River dug out the Grand Canyon but continually made and remade as vents open and close and the fragile columns topple. They look exactly like the drip castles I made in the mud at the Jersey shore during my childhood, but magnified to impressive heights, and constructed not of dried sand but of the precipitated volcanic fluid emitted from the fissures. I keep reflecting on the dozens of smoking pillars and the chaotic marvel they provide.
The time has come to ascend back to the surface and leave this world beneath the sea behind. Before doing so, however, we must transit off the primary axis of the vent, away from the active spreading center chock full of these wondrous features. We make our way to the pillow lava plains to the east, an area of rolling mounds of cooled lava. The pilot offers to let me take the stick, ignorant of the fact that I haven’t even driven a car in the last dozen years, but happy to show me how to accelerate and decelerate and turn and change the sub’s altitude. For 15 joyous minutes, I drove across the lava plains, meandering about and getting a feel for what is surely the most extreme vehicle I will ever operate. We pass over a huge anemone, but the moment is fleeting and it is gone before I have a chance to stop. A few crabs here and there, but at this point, I am consumed not by the biology, but by the magnificent joy of darting about in a tiny sub at the bottom of the ocean. In no uncertain terms, it was the perfect ending to a most dreamlike day.