The view from 5 km below

Tuesday, July 2, 2013 - 13:42
Yesterday I went to a place that has been visited by about as many people as the surface of the moon.  The moon has had 12 sets of human feet walk upon it.  The Beebe hydrothermal vent field, home to the deepest and hottest vents in the world, has now seen five scientists and eight pilots.  I'm writing this post aboard the Japanese research vessel Yokosuka after diving on the submersible Shinkai 6500, nicknamed 6K.  I am humbled and in awe of the sights I have just seen - there are no words to do justice to this experience, but that won't stop me from trying.
I was in the hangar at 6 a.m. donning an astronaut-like uniform, in the sub at 6:30 watching the heavy hatch get screwed into place, and we began our descent at 7 - precisely on time.  I am joined by two men, the pilot Sasaki-san, and the copilot Suzuki-san (like the cars and motorbikes, he tells me with a grin).  There is no heating or cooling system inside the 6K, so as we bobbed like a cork in the waves, it became quite hot inside despite the sun still being low in the sky.  However, as soon as we left the surface, the metal sphere that protected us from the crushing pressure of the ocean became cold to the touch and dripped condensation, and I was thankful to be sharing the tiny space with two other people and banks of electronics, each putting out heat.
The 6K does not use propulsion to descend and ascend, instead relying on the simple physics of buoyancy to move without drain on the batteries.  Loaded with iron ballast and a large tank that was pumped full of seawater on the surface, we sank, quite literally, like a rock.  At 7:05, we passed the 200 meter mark - a depth often used by oceanographers as an estimate of the bottom of the photic zone, that is the depth beyond which photosynthesis cannot occur.  The blue outside my porthole had already changed from brilliant to vibrant to deep to inky.  At 7:11 and 456 m according to our instruments, I noted that the scientific payload was no longer visible to me - the sunlight was now too faint for human eyes, even ones that had been adjusting to the dark and looking for a brightly reflective surface.  At 7:23, there was already 1000 m of seawater above me, more than half a mile.  I had left what oceanographers term "the twilight zone" and was now in "the midnight zone", a place of perpetual darkness, untouched by the sun.
Except it wasn't dark.  Outside my porthole, a light show was going on.  Bright blue bioluminescence shone from animals from the smallest zooplankton to larger jellies and fish.  From my perspective, the outlines of the animals were invisible, only flashes of blue in various shapes and sizes were to be seen.  It was hard to tell we were falling without looking outside, but the lightshow was streaking past us, often moving (from our perspective anyway) so quickly that my eyes couldn't focus on an animal before it was out of view above the sub.  Occasionally one would get caught in an eddy and swirl around my porthole flashing brightly before getting swept away.  We passed 3000 m sometime just past 8 (I had been too caught up in the fireworks display to make a note).  The pilots turned on the sub's headlights and began testing the scientific instruments and cameras.  All but the brightest bioluminescence was drowned out, but the unidentifiable flashes were now replaced by otherworldly creatures - a small red shrimp with antennae several times longer than its body and ctenophores with the cilia that they use to swim reflecting rainbows of light, along with many other jellies and small invertebrates that were ghostly white in this world where vision is of limited use.
Somewhere along the way, Suzuki-san handed me a plastic box with my name on it, and I scarfed down a couple of fish-and-egg sandwiches before returning my gaze to the tiny porthole.  I looked at the thermos of tea that came with breakfast, but decided it was better to wait until I was at least within a few hours of the surface and a toilet.
At 9:00, two hours after I'd left the surface, we were past 5000 m, and stopping to drop ballast and adjust the trim in the water tanks, matching perfectly the density of the water around us to make maneuvering in all directions require the minimum of power.  A few minutes later, I could see the seafloor in our headlights, and then dust was rising around us as we settled just one meter above the ground, now at 5135 m, the deepest reading I would see on the instrument panel.  I immediately saw purple sea cucumbers, bright white anemones and delicate brittle stars - another alien realm, as different from the water column as from the surface world above.
Immediately, the pilots got to work, first with a radio call to the surface to let them know we'd arrived and get our precise location (they triangulate it based on a ping signal we send and their own satellite GPS - inaccessible from beneath the water - so we don't know where we've landed without asking), then pulling out bathymetric maps with ruler and compass to calculate our path to the target site.  Suddenly it feels very low-tech, and I'm reminded of sailing ships calculating their location based on nothing more than the sun and stars.  Before I know it, the pilots have placed us and drawn a route on the onboard tablet computer, and I'm jolted back to the 21st century.
It took only a few minutes from our landing site to the area known as Anemone Field, an area where warm (but not hot) hydrothermal fluid seeps slowly from many cracks and crevices, creating a shimmering look to the water the same way that roads sometimes shimmer under the summer sun.  The pilot takes a remote control with two multi-jointed arms sticking out of it, and one robotic arm deftly picks up a spool from the tray on the front of the sub while the other grabs a fine wire off the seafloor and begins threading it.  Despite the pilot's great skill, this is a touchy operation - recovering something that was never meant to be here in the first place, an optical fiber accidentally cut on a previous dive - and the wire breaks and requires re-threading several times.  I am in charge of one bank of cameras, keeping them pointed at the manipulator arms so the co-pilot, who has no view of the work outside through his porthole, can follow the pilot's movements, slowly creeping the sub forward with another controller so that the wire maintains enough tension to spool, but not enough to snap.
It's 11:00 before we're finished with work at Anemone Field, and on the way to our second site, called Hashtag.  It's then that I get my first view of "black smokers", tall chimneys spewing super-heated fluid full of dark sulfide particles.  Another incredible view, and another strange world - this one filled with pure white animals, all of which depend on bacteria who "eat" the chemicals in the vent fluid.  Small white shrimp are so abundant that you would think the chimneys are white rather than black from a distance, but as we move closer it's obvious they aren't alone.  White fish hover just off the chimney walls, and cooler areas are home to squat lobsters and large anemones.  Before we begin spooling wire again, we switch gears and work on science for a moment.  First, pressurized bottles are opened and pumped full of hydrothermal vent fluid - our temperature gauge tells us it's 396 degrees Celsius.  Then, the manipulator arms delicately snap off a piece of chimney and place it in a box in the instrument tray.  I'm still amazed at how gracefully these huge metal arms can move under the control of a skilled pilot.  After that, it's back to spooling cable.
Around noon, we arrived at our final site, Beebe Woods.  Here, the optical fiber was draped straight over the top of a chimney, forming a Christmas tree shape toward the seafloor on both sides.  But before we picked it up, we grabbed another water sample - it's relatively low, just 320 degrees this time, but still 220 higher than a boiling kettle on the surface.  It seems like a blink of the eye later, we get a radio message from the ship - it's 1:00, and time to head back.
Once again, we're flying quickly through the water, watching flashes of light zip past the porthole, but this time they appear to fall.  At some point I get another plastic box from Suzuki-san, lunch time.  Rice balls with sour plum, salted tuna, pickled daikon and omelet, yum!  Around 500 m, I see the equipment slowly appear out of the dark - the sun is higher now, so light is penetrating just a bit further. 
Soon we're up, and again we bob on the surface, being tossed in every direction by the waves.  Despite waiting a day for the weather to improve, these are the heaviest seas that the 6K was deployed in on this cruise.  Out the pilot's porthole, the ship's propellers are spinning - strange, but this is the first time I've felt scared, despite knowing that they were serving to keep the ship precisely positioned against a current and not to steam away or chop us up.  Soon, I hear footfalls on the roof, and a strange squeak as the divers fasten the huge ropes to the sub, and before I know it, we're being lifted out of the water.  The clock says it's 3:12 as we land in the cradle on the back deck of the Yokosuka, just a few minutes later than planned.
As soon as the sub is secured, those propellers go to full speed and we're on our way to Panama.  We're half a day behind schedule due to the rescheduled dive, so there's no time to lose.  The hatch is slowly opened with a hiss of air and a popping of ears, and a narrow ladder is lowered in.  Having not straightened my legs in nine hours, the short climb is actually a bit of a challenge, and I stumble on the ramp that leads from the sub to the ship's deck - the rest of the scientific party are below snapping pictures of my return and there's a collective gasp, but I catch myself and pause to smile for them.  I know what's coming next, and it requires me to return my uniform and step out on deck in the pajamas I'd had underneath.
There's a bit of confusion over where I should stand - the crew of the 6K are on deck welcoming back Sasaki-san and Suzuki-san, but they want no part of this.  Suddenly it hits me - the first bucket of cold water, right in the face.  It's followed in rapid succession by about twenty more, and each time I think it's finished, someone finds another.  Takuya, a Japanese student who did not dive on this cruise, gets a little too close and takes a couple bucketfuls as well.  To be honest, the chilly water is quite refreshing, as the sub had heated up again while we waited for the hatch to be opened.  It's a rite of passage for all first-time divers, and I'm all smiles as I drip my way back to my cabin for a change of clothes.