While this happened a week ago, I wanted to take you all on a journey with me to the deep, as I had the privilege to dive with Alvin last week. This post is longer than usual (~20min read). If pictures and videos are more your thing, the story is told through them too!
Pre-Dive
The dive day starts the night before. The first thing each diver must do is pack their bag for a whole day under the surface. In a blue crate in the Alvin hanger, we fill a pillowcase with all the essentials – a pen, a clipboard with notes on our science objectives, navigation targets, and reference images, and 100% natural fiber clothes. We aren’t allowed to bring in any electronics unless they’ve been properly tested, but it’s nice to leave the phone behind. Since Alvin is not temperature controlled, it’s best to pack a sweatshirt and a hat, many of us have red “Cousteau” hats made by loved ones (thanks mom!), but start in the sub with pants and a light t-shirt due to the tropical heat.
In the morning I went into the main lab, first needing to attach Dan Fornari’s MISO camera to the brow of the sub, as I’ve done for every dive. This camera allows us to take 5.3k images every 5 seconds during the entire dive. After fulfilling my duty, I went up to the galley and joined the rest of the science team in getting a full belly for the day ahead. While some try to limit the amount of food and water they consume before spending 8 hours in a 2-meter diameter sphere, fearful of needing to use the bathroom, it’s better to just be hydrated and full. If you need to use the pee bottles in the sub, that’s what they’re there for. We all moseyed to the aft deck where the Alvin team was finishing up preparations: removing the covers on the windows, securing the basket, and checking systems. I stand next to my science observer partner, Lauren Dykman (LD), and our pilot, Bruce Strickrott, and chat with our fellow scientists about the dive ahead, and our excitement. Alvin is wheeled out under the A-frame, a bridge swings out from the staircase and onto Alvin. The Alvin Launch Coordinator calls for the pilot, to begin checking the interior systems, and Lauren and I wait in anticipation, and of course taking a few pictures together in front of the sub. The call for observers signals us to make our way inside. We climb the staircase, turn around, give a wave, take off our shoes, and climb into the submersible.
Inside, I move to the starboard (right) side, and LD to the port (left) side. Memory foam cushions with blankets on top welcome us, along with iPads for controlling the camera system, small handheld cameras, and our pillowcase day-bags. We exchange animated glances as Bruce finishes up the necessary checks, and the hatch seals shut. Here we go! Alvin is lifted into the air, gently shaking the sub, and is lifted over the water. A loose drawer swings open, and I hold it shut as Bruce yells at it to behave. The sub lowers into the water, feeling akin to the top of a rollercoaster, and bubbles fill our viewports as we make splashdown. As the bubbles clear, we see Alvin divers releasing the basket lines, and disconnecting the main and tow lines above. With the go ahead from the team, we begin our descent. Bruce starts a playlist, and we watch as the light blue ocean turns green, then a dark blue, into black. With a 2500m descent to the bottom, we’ve got nearly an hour and a half before we see the seafloor. LD and I go over the dive plan, familiarize ourselves with the camera and data logging system, while Bruce relays our depth and tells us stories of dives and adventures past. The ocean outside our viewports is not so dark though. Flashes of bioluminescent organisms shine blue and green. A firework show as they disappear out of view. We excitedly shout out the largest jellyfish and siphonophores we see and scan the darkness for new creatures.
Reaching the Seafloor
Then, we see it! Not the seafloor first, but the bright yellow lander platform we launched the night before, with our plankton pump and niskin bottle water samplers. It blinks in the distance and the seafloor comes into view. Made up of hardened lava flows and sharp fragments of volcanic glass, it glistens in the sub’s lights. We approach the lander, move some weights around, and pick it up with Alvin’s manipulator arms to move it to our study sight. As we head east, I trace the lava flows that show a clear direction of motion, picturing the molten formation. Maybe it was from the eruption at this site in 2006. We begin to see some formations on the horizon in front of us: small mountains, and cliffs. As we get closer the structures change into more biological shapes. Groups of Bathymodiolin mussels, and massive clusters of Riftia tube worms begin to surround us as we approach our target site for this dive, Tica, it’s called. We place down the elevator, pull the tabs of the niskin bottles, collecting samples of water from the site, hoping to capture free-living bacteria, and Bruce calls for a break.
I reach behind our CO2 scrubber and pull out individual boxes labeled for each of us. Inside, our wonderful cook Susan has prepared us each two sandwiches. Bruce excitedly pulls out his peanut butter and honey sandwich, proclaiming to me and LD how it’s the best kind of sandwich for deep sea adventures, with bread perfectly saturated with the honey. We laugh and observe the incredible ecosystem we’re merely inches from as we refuel. With squat lobsters, eelpouts, barnacles, and small snails crawling around the dominating tubeworms and mussels, there’s so much to watch, it’s so alive down here. Then, Bruce notices something else. A tiny octopus, called Vulcanoctopus hydrothermalis, a hydrothermal, volcanic octopus. This small, white Cephalopod crawls around the rocks as Bruce lines up my camera to capture a 4K video. Nancy, we called it, sets their sights on a gelatinous creature near the edge. Nancy attempts to grab it, but it’s a swimming sea cucumber that expertly thrashes away and is carried by the current. Nancy, defeated, retreats to a hole, they’ll try again later.
The Science Begins
Unlike Nancy, we were successful in our consumption, and it was time to do what we came down here to do, to deploy science equipment so we can study these bizarre habitats. Bruce flies the sub over to the first of our three biotic zones, the suspension zone, a cliff where we had deployed pursed “sandwiches” on a previous cruise, and tube traps on a previous dive. On the brink of this hydrothermal community, less impacted by the warm, nutrient rich hydrothermal fluid, there are fewer organisms. Serpulid tubeworms and squat lobsters litter the rocks and some jump away as we approach the cliff side. Our first objective was to open these purses and redeploy the sandwiches that are inside. Bruce picks them up to move them closer to the tube traps we want to deploy next to, but on the last one, it slips, and tumbles down the cliff. We’ll try to get it later. Bruce uses both arms to grab the purse handles and pull the Velcro apart, revealing a sandwich that’s hopefully developed a bacterial biofilm. He delicately grabs the loop, and places it next to a tube trap.
During each deployment, LD and I keep track of the sample ID so we know what’s down here, and the history of them when we analyze them later. While she writes down the coordinates, heading, and ID down on a written data sheet, I update our digital data logging system, SeaLog. With each unpursed sandwich, Bruce reaches into a box on Alvin’s front basket and adds a freshly built sandwich next to it. We are creating clusters of two sandwiches and a tube trap, hoping to identify the impacts of biofilms on larval settlement, and the larval supply in these different zones. For robust science, we do four sets at each zone.
We decide to find the purse we dropped earlier before we move on. We have time, but it’s not going as we had hoped. We spot where the purse had fallen, down into a gorge. We circle around into the right position, where LD and I act as Bruce’s eyes out our side viewports, calling out the distance to rocks and animals, careful to not hit anything. As we descend, we realized that this is the heart of the East Pacific Rise. In the middle of two diverging tectonic plates, we are at the lowest part of Tica. Outside my viewport, I’m face to face with the seafloor, LD has a cliff face. We are barely able to fit in here. Towering above us is a pillar of sulfide rocks, with Alvinellid tubeworms popping in and out of their tubes. In the background are walls of Riftia and mussels, with eelpouts snaking in and out of view. I think about how much we can see from the submersible, but that this ecosystem is usually in complete darkness. I start to think about how different this ecosystem is from ours, how incredible it is that we can visit this harsh environment that humans were never adapted to see. Questions swirl in my mind. Why do these eelpouts even have eyes? Do they see differently? How do these animals interact with each other and what do their lives look like?
Bruce finds and recovers the purse. We return to the cliffside and attempt to open it. We run into an issue, however. The purse handles rip off, without opening the Velcro. Luckily, Bruce and our team anticipated this issue and brought Alvin weapons! There were two knives attach to metal T-rods, easy for Alvin to grab, that we could slice open the purses with. He grabs the first knife, but it shatters as it hits the side of the basket. Darn. He grabs the second knife, and woop! It slips right out of the claw and falls under the basket. We back up to try and see it, but it’s rolled off the cliff as well… I guess we move to plan B. It was time for Plan Bruce. Grab the metal t-rod and shove it through the purse. After a little struggle, the purse is ripped to shreds, and the sandwich inside is recovered unharmed. Good thing we have more purses and even when ripped, we can recover what we need from them. We deploy the final sandwiches and begin moving to the next site. As we leave the suspension zone, we look for the dropped knife. We spot it, but it’s just too far out of reach to recover safely, so we turn around and head for the next biotic zone, the mussel zone.
This area was more challenging to get into. On the port side, LD faced a large wall of Riftia tubeworms, actually where our third biotic zone is, and on the starboard side I had a sulfide spire, which we nicknamed “Hobo Spire” for Dan Fornari’s HOBO data logger measuring it. It’s nearly 4 meters tall, but very narrow so we don’t want to hit it and knock it over. There was one set of sandwiches and tube trap already deployed here, and two purses that had previously had their handles fall off, hence why we had the knives originally, and one purse that had gone missing from when we had deployed them in 2021. We nestled next to the spire where I scanned it up and down, mesmerized by the Tevnia tubeworms at the base, and the shimmering diffuse hydrothermal fluid, aware of the heat of the water. As Bruce opened the purses with the same T-rod method, LD and I traded using a handheld camera to take photos of each other and the habitat we were within. I captured a moment where an Alvinellid worm was attacked by a Paralvinellid tubeworm, perhaps a territorial display, or perhaps something more sexual. These animals are thought to be the most thermally resistant animal on the planet, existing at the heat limit of when the mitochondria starts to break down.
Unfortunately, while unpursing, one of the sandwiches inside had broken, but impressively, Bruce picked up the plates delicately as if they were made of porcelain and put them in a stack so we could still use them. These were certainly not the easiest deployments for two robotic arms to work with. Still, Bruce worked expertly. We then shifted to try and find the last purse which we couldn’t find from where we had parked Alvin, so we decided to try to approach from the other side. We backed out from between the wall and the spire and did a large, rising circle to get around the difficult bathymetry of this site. Since 2021, Tica had changed tremendously. Not only were there far more animals than last time, but new sulfide spires had popped out of the ground, making navigating even more challenging. Others had referenced it as a forest of Riftia and sulfide spires. Even still, Bruce knew exactly where he was going, pointing out landmarks like “Tica Prime”, a huge sulfide pillar with a colony of tubeworms jutting off the side, or “Bishop Spire” that looked like the bishop chess piece. As we circled around, LD and I commented on the topography of this site, there was incredible depth to this site that pictures and videos can’t quite translate. From the sub you can see levels below and cliffs far above. As we say this the sub jerks as we bumps a rockface that we couldn’t see below us, reminding us to be careful. We tried to get to the backside of the mussel zone, approaching from the north side, but we didn’t see the sandwich and didn’t dare to get too close to the spiky seafloor.
We decided to finish up what we could and stopped at the Riftia zone on the way back to the mussel zone, since they were right next to each other. While we had also lost two purses here, the Riftia had grown so much we assumed they had grown over them and did not want to crush and tear through the animals to find them. We assumed that this was the same fate the mussel zone purse had faced. Instead, we just deployed the final two paired sandwiches with no problem next to the tube traps we had deployed on an earlier dive. Using Dan Fornari’s MISO camera photos, and a Python coding script LD had made, we made a little timelapse of how those deployments looked.
Finally, we returned to the mussel zone, squeezing next to the “Hobo Spire” once more, and deployed our final paired sandwich and one more tube trap. Now we had completed the deployments for all the zones at this site. We will leave these down here for nearly two weeks and then we will recover all of them before we leave the EPR at the end of the cruise. Feeling accomplished, and with drawn maps of all our deployments and the main objectives complete, LD and I informed Bruce we could now move onto opportunistic, ancillary objectives. We wanted to collect some mussels, and potentially some sulfides with Alvinellids that one of the Principal Investigators (PI) on this project and cruise, Costantino Vetriani and his lab could use for isolating bacteria from these sites and grow them. Unfortunately, while we were looking for a collection site, we realized we were running low on battery, and it was time to return to the surface. Had it really been nearly 8 hours already?
Reluctant to leave this bizarre and beautiful world we were exploring; we began heading west. When Alvin ascends, stacks of weights must be dropped, so we always try to leave the study site and avoid impacting the community when doing so. As we leave Tica, Bruce exclaims and points out the window. There we see a giant sea anemone called Boloceroides daphnae, that can have a diameter up to 2 meters. These are rarely seen, and this large purple one had tentacles that trailed in the current for many more meters. We admired it but quickly changed focus when we saw a large, coiled line that was unmarked. If we hadn’t seen it, future dives could be at risk of entanglement, so we called up to top lab (the Alvin team on the ship end of the communications), and marked down the coordinates.
We then left the site and got ready to ascend. LD called up to top lab to Costa and relayed our science report – what objectives we had completed, and if we were bringing up any samples that our team should be ready to receive. We had purses, but no live animals and no suction samples, so there wasn’t much to recover when we got back on deck. It was incredible that we were able to communicate so easily to the ship 2500 meters above us. Bruce then confirmed if we were clear to leave bottom, and he offered me the opportunity to be the one to drop the weights. I stood up, for the first time in 8 hours, primed the release, and dropped one set of weights on the starboard side, and the on the port side, and just like that we began to ascend.
Returning to the Surface
With another hour and half ascent time, we could just relax, listen to some music, and talk about the dive. We ate our second sandwiches, turkey and cheese this time, ate some molasses cookies we snuck on, and still wondered what was for dinner. During all this free time, it was a good time to take care of all our bodily needs including using the restroom. While I had gone earlier, Bruce and LD grabbed a bottle each, accommodating for all genders, and put up a privacy curtain while Bruce searched for the “perfect song” to hide the sounds. I intensely stared out the window while business was taken care of, and then we all came back together. After spending a whole day together in ~34m2, awkwardly bumping one another and accidentally playing footsie, we were very comfortable with each other. During the rest of the ascent Bruce told us about his history as a pilot, some stories of other dives, and we talked about vacationing in Costa Rica.
As we returned to the surface, watching black turn to dark blue, to green, to light blue, we were welcomed back by the Alvin swimmers. They secured the basket, attached the sea anchor that helped us control our surface speeds, and helped direct Alvin towards the back of the ship. As we bobbled on the surface, I started to feel a little bit seasick, with more light than we’d had in a while, and being in a lower oxygen environment. I was eager to get out of the sub, but still enjoying every moment being inside. Once we reached the A-frame at the stern of the ship, we were picked up and lowered back onto the deck, into Alvin’s “sled” that moved it in and out of the hanger. We waited as the Alvin team secured us and started assessing the sub for any damages. (We may or may not have gotten a scratch on the side when we were circling the mussel zone.) While the sub warmed up from being out of the water, the sphere began to condensate, a light tropical rain came down from above. Then, we heard the hatch open, fresh air flowed in, and they lowered the ladder for us to climb out. First went LD, then I climbed out. We waved and exclaimed as we walked off the sub to the rest of our team cheering from below, taking pictures and videos of us returning from the depths. I hurriedly put on my shoes, fumbling the laces with everyone watching me, and we climbed down the stairs on our wobbly legs to recount the dive and our successes. Since LD and I had both had Alvin dives before, we didn’t get any surprise buckets of water dumped on us, but this dive was certainly the most spectacular we’d ever seen and it felt just as momentous.
We watched as the sub rolled in, retrieved our opportunistic science that we didn’t get to from the basket, I brought in the MISO camera, and we all headed to dinner. After dinner we held our regular science meeting, where LD and I reported on the science portions of the dive, and we began getting ready for the next dive. We’re diving everyday for 20 days straight to get all our goals for this cruise done.
I wanted to share with you the experience of one of these dives, to highlight the magic of these expeditions into the depths. See you next time!