2,500 Meters Down

Dive AL5147 - My first dive in the Human Occupied Vehicle (HOV) Alvin

January 20th, 2023

After reviewing our dive plan one last time with all the scientists, making sure we’d covered every sampling objective, I packed my wool hat, sweater, and a notebook with a photo of my husband and I, and a 'Happy Birthday' sign for my Dad, into a pillowcase. We had to drop it off the night before, so the crew could load it into the sphere early in the morning. I’d be lying if I said I slept well that night. I was too excited, it invoked the childlike feelings of the night before Christmas. I put on my ensemble the of 100% natural fiber clothing, as flammable materials are a strict no-go, opting for extra-large, cozy pajamas. Breakfast was intentionally light, just yogurt and toast, low-risk to avoid any digestive dramas as we were all recovering from a norovirus outbreak on the ship (Alvin's bathroom is a she-wee/portable urinal combo, or plastic bag).

The sun was rising above the horizon and quickly warming the ship's deck. The quiet stillness of early morning began to shift into the controlled chaos of a dive day. The longest part of the day is the wait: waiting for all the checks, for Alvin to roll out of its hangar, for the team to loop the rope around the sub’s top. First comes the call for the pilot to enter the sub and complete internal checks, preparing the sphere for the observers. Finally, we heard it: “Observers!” My pulse quickened as I walked across the deck, climbed the welded-on staircase, slipped off my shoes, and waved goodbye to those watching on deck.

Boarding Alvin felt surreal. The first step is tricky: you swing one leg around the sail, sit on it, and then carefully bring your other leg over, all while minding the large open hatch. Holding onto handles in the sail, I lowered one foot onto the ladder, cautious not to kick any of the delicate electronics. Each step down felt deliberate, grounding, and unforgettable. The bustling noise of the deck and the ship’s engines faded, replaced by the soft, steady hum of the sub’s systems, and the ship’s commotion of scientists and crew felt worlds away. Our pilot was playing their carefully curated playlist, the kind of music reminiscent of boarding a plane. It was just the three of us, sealed into this small, intimate space for the next eight hours. With only about two square feet to work with, I maneuvered around the pilot and dive lead’s legs and found a spot to sit on the sphere’s floor.

Our pilot, well over six feet tall, craned his neck as he carefully inspected the hatch’s lining. Every speck of dust, hair, or debris had to be removed as it could compromise the seal. Once the hatch was secured and the pre-dive checklist completed, it was time for lift-off. The A-frame hoisted Alvin off the deck, and the submersible pitched forward. We found ourselves gazing straight down at the shimmering sea surface as the lift line creaked and tightened around Alvin’s signature “T”. Moments later, swimmers released us into the water. That’s when it truly hit me, we were about to descend 2,500 meters into the deep, heading for some of the most extraordinary ecosystems on the planet...

As we descended to the seafloor, the experience felt almost out of body. I cupped my hands around my face to block the light inside the sub and peered out the viewport. Flashes of green bioluminescence lit up the darkness, and I let out an audible gasp when I briefly saw the shape of a glowing, swimming polychaete. I tried to ground myself in the moment, focusing on the fact that we were free-falling through miles of water, with an unimaginable amount of ocean above us and the seafloor still far below. I wanted to fully appreciate the space I was in, but it was hard to grasp.

“Approaching bottom,” the pilot said. “Let me know when you see the seafloor.”

At first, all I could see was the blue haze of the water column illuminated by the sub’s lights. But within seconds, the volcanic basalt began to come into focus. Glassy, shiny obsidian cracks reflected the light. Then, almost on cue, the song "Float On” by Modest Mouse began to play, a perfectly timed moment on the playlist. Immediately, I spotted a large, distant Bathysaurus, floating just above the benthos, eerily still. The slow movements, adapted to conserve energy in freezing, high-pressure conditions, were mesmerizing. But it was when we came right up to a stalked crinoid that the moment truly hit me. I’d seen crinoids on basalt in countless ROV videos, but here it was, three-dimensional and alive, its arms gently swaying with the currents. The landscape was unlike anything I’d imagined. I thought I had a grasp on the basalt flows of the East Pacific Rise from video footage, but this was entirely different. Being among the dynamic topography of lava flows and seeing the animals tucked into its bumps and crevices firsthand, and seeing the sparkling lava glass in was transformative.

Above images: (Left) Relicanthus daphneae is a common animal found on the surrounding basalt; its tentacles can reach up to 3m long. (Right) Alvin illuminates the seafloor of cooled lava from previous eruptions.  (C) Woods Hole Oceanographic Institution, National Deep Submergence Facility and National Science Foundation

Navigation at these depths requires careful planning and consideration of the strength and direction of currents throughout the water column. Our first target was the lander, equipped with science equipment and a camera setup that we had deployed about an hour before our descent. However, the currents had unexpectedly picked up speed overnight, and the lander had drifted a considerable distance from our target point. The search and recovery used up precious battery power that would later limit our time at the sampling site. With the lander finally secured, I watched through the porthole as Alvin glided over the volcanic landscape.

Gradually, subtle changes began to appear in the terrain below us: delicate microbial mats threading through cracks in the basalt, indicating diffuse flow through the porous basalt. This was our first indication that we were approaching more vigorous venting activity.

The microbial fluff was followed by munidopsid squat lobsters, scuttling across the increasingly colonized seafloor. The mussel beds emerged from the darkness, leading our eyes to the magnificent Riftia-covered tower. The scene exploded with life, and I immediately noticed approximately twenty zooarcid fish engaged in a feeding frenzy over mussel or Riftia tissue. The Riftia themselves were much larger than I imagined, their tubes stretching well over a meter in length.

Our first priority was documenting the site. We needed precise imagery for 3D reconstruction to track how these spires evolve and grow over time. As we methodically scanned the towers from bottom to top, the slow pace allowed us to absorb the site's intricate details: hundreds of Riftia tubeworms with their associated communities, the ethereal, iridescent microbial mats draped over the dormant spire, and the mesmerizing flow of hydrothermal fluids through the beehive structures. In the warm flow zones, Alvinellid worms clustered in dense colonies, thriving in conditions that would be lethal to most life forms.

We proceeded to sampling by collecting a beehive structure, aware that it would regenerate within the year, and we also gathered fluid samples from the vent opening using Isobaric Gas Tight chambers (IGT). The samples collected during this dive and others during this cruise led to an accurate model that correctly predicted its eruption in 2025. The sounds inside Alvin are far from quiet; gentle whirring with every movement of the sub, hums of the CO2 scrubbers, all set against a backdrop of music. Here is a video clip showcasing the typical sounds you hear while preparing the sub to collect a sample:

After securing our second fluid sample, our pilot's announcement about Alvin's dwindling battery came as a surprise. Time had warped in the sphere, we'd been so engrossed in our work that we'd completely forgotten about lunch. Though we'd only completed a fraction of our objectives, each maneuver had required precise calculations and patience: adjusting ballast, shifting water between tanks, and carefully manipulating Alvin's two robotic arms. The complexity of these operations, combined with the otherworldly environment we were exploring, made the hours slip away like minutes. Our pilot released the weight on the lander, and it slowly began its rise to the surface, and now we had to wait for the elevator to be recovered by the ship before we could surface ourselves.

Out of caution to conserve battery, we turned off all unnecessary electronics and sat at the bottom in the darkness until we received the final clearance to drop Alvin's weights and ascend. I have heard of many scientists who sleep on the way up, but this time I kept my eyes glued to the viewport to watch for bioluminescence and any other charismatic megafauna. For most people, the most uncomfortable part of an Alvin dive is once you're at the surface. Because we were diving near the equator, the sphere's temperature rose quickly, and we were left bobbing up and down with the waves. The port windows remained submerged about three meters below the surface, so there was no horizon to look at to quell any motion sickness. My coping strategy was to brace myself, close my eyes, and convince myself I was on a swing.

The process to recover Alvin is relatively quick and involves many checkpoints and crew members. Once Alvin surfaces, a dinghy with two to three recovery swimmers jets off to meet it. Two swimmers jump into the water and climb onto the sub's orange sail, reaching in to communicate with the pilot using a sound-powered phone. Other swimmers secure the sub's basket that holds the science equipment, then latch a line to the sub that's connected to Atlantis. The sub essentially gets reeled in line with the ship so that the rope on the A-frame can be secured to lift the sub back onto the deck.

Once we were latched back onto the tracks on deck, the relief hit, and we waited for the crew to unseal the hatch from the outside. Our ears popped from the pressure difference once the hatch opened. The ladder was then lowered back into the sub, and climbing out could best be described as feeling like a baby giraffe walking for the first time. Just like that, my first dive was over as I slipped my shoes back on and headed down the stairs to tell our science team the details about our dive.

Footage from this dive was featured in BBC's Planet Earth III Episode 2: "Ocean" and in the short film "Immersive" by Rohan Thomas and Thibaut Barreyre.

The National Science Foundation, the main funding source for HOV Alvin and its sole support vessel, R/V Atlantis, is facing significant funding reductions proposed by the current administration. Please contact your representatives to advocate for the support of all scientific research in the US and insist that no reductions be made to the budgets of the National Science Foundation (NSF), National Institutes of Health (NIH), and National Oceanic and Atmospheric Administration (NOAA). The ability of scientists to utilize Alvin for research is at greater risk now than ever before.

More about Alvin's operating and funding structure:

While Alvin is technically owned by the U.S. Navy, it's operated by the Woods Hole Oceanographic Institution (WHOI) in Massachusetts, with the National Science Foundation (NSF) providing the primary funding through cooperative agreements. This unique partnership means that no single institution has to shoulder the enormous costs of maintaining and upgrading such an advanced piece of technology.

The system works remarkably well for the broader scientific community. Alvin operates as part of the National Deep Submergence Facility, which makes it available to researchers from universities and institutions across the country. Scientists submit research proposals to NSF, and if their projects are funded, they can request dive time aboard Alvin. It's part of a larger fleet that NSF supports: 18 research vessels and 3 submersibles that serve as floating laboratories for American researchers.

Since its launch in 1964, this funding model has proven incredibly successful. Alvin has enabled over 3,000 scientists to make more than 5,200 dives, leading to groundbreaking discoveries like hydrothermal vents and contributing to nearly 2,000 scientific papers. The recent major upgrade, which cost $21.6 million and enhanced Alvin's diving capability to 6,500 meters, allows access to over 99% of the world's seafloor. WHOI even contributes its own funds for enhancements and operating costs, demonstrating the collaborative spirit that makes this program work.

This arrangement democratizes access to one of the world's most advanced exploration tools. Rather than being limited to wealthy institutions or corporations, Alvin serves the entire American research community: funded by taxpayers and operated by experts, all in service of expanding human knowledge about our planet's last frontier.

Sources:

• Woods Hole Oceanographic Institution - HOV Alvin overview

• Wikipedia - DSV Alvin

• National Deep Submergence Facility

• NSF Exploring Hidden Depths