We could no longer see remnants of land – the soft, evening glow of ordinary life had dimmed and disappeared. We were far out to sea, enveloped in a permeating darkness. The ocean twinkled as we coasted through the gentle swell, as if the stars had been cast into the sea around us. I stood at the bow of our ship looking down, a smile plastered across my face. The movement of the ship triggered a biological light show, performed by bioluminescent plankton. Brief flares of light erupted beneath us, fireworks bursting beneath the surface as we headed to our destination – the Revillagigedo Archipelago.

From the depths of the Pacific, some 250 miles southwest of Baja California, four volcanic islands emerge. Between them, an underwater epicentre of biodiversity and activity bustles. Aggregations of manta glide around freely alongside whale sharks and dolphins. Juvenile whitetip reef sharks pile on top of each other in rocky crevices. Schools of critically endangered scalloped hammerheads meander around at dark depths. Humpback whales, migrating from Alaska, have mated and calved in these waters for thousands of years. Yellowfin tuna thrive without outstanding pressure from fisheries. Several of the species that reside here are found nowhere else in the world. Sheer isolation and lack of human influence have kept this spot in pristine condition.

Sleeping on a moving boat is an unusual task, the constant pitching forward and backward, side-to-side, induces a sense of vertigo only exacerbated by closed eyes. I slept very few hours that first night, lost in a spin of confused equilibrium. At a reasonable morning hour, I made my way topside, somehow managing two sets of ladders. I looked around. I saw just endless miles of sea, now bathed in golden light from the morning sun. We still had a full day of travel ahead of us. The crossing can take around 30 hours and we had only been chugging along for 10.

Eventually, there was a void of sound where the engine once hummed, white noise that had become all too familiar, comforting even. We had stopped moving forward, though we still periodically bobbed from side to side. The anchor was set. I finagled my way out of the bottom bunk and, again, ungracefully climbed up a set of ladders to the main deck. To my left, through a window, abruptly emerging from the sea was a stark, ashy white island. San Benedicto. Breakfast was served and we would soon be underwater. And so our new daily routine began: eat, dive, break, eat, dive, break, and so on.

Getting into the water always provided an exhilarating rush. Packed tightly into a small boat with scuba tanks strapped to our bodies we rode out to our drop point. After a somewhat frenzied effort our captain would give the countdown and we would roll collectively backward into the water. Timing was crucial. Not only were we keeping the boat balanced, but surface currents can be strong out there; it was best practice to descend immediately upon hitting water and check-in at depth. A negatively buoyant entry.

My vision became obscured by a chaotic rush of blue and bubbles. Water seeped into my wetsuit and I shivered instinctively at it slow trickled down my spine. I equalised my ears and kicked downwards, trying to avoid the fins of others doing the same. Things calmed. Silence took over. A silky shark meandered through the commotion. At 20 feet we checked in. Signalling “ok” to one another, adjusting any gear that needed it.

There were just fewer than 30 of us, divers and crew, on this particular expedition. We came from many corners of Earth, tethered to one another not by proximity or a shared language, but by a mutual love for the ocean and for diving. Diving is a quiet activity. Mostly, we swim in silent observation of our surroundings, searching for moments and encounters so striking it brings us to a pause: to relish in a state of mutual awe. These moments came frequently at Revillagigedo – perhaps most regularly from interactions with the manta rays.

They seemed to emerge from nowhere. Sometimes they were curious, sometimes playful and sometimes they merely passed by en route to somewhere beyond the reaches of our vision. It was the 13^th dive of the trip that I stared into the eyes of a manta ray. At 60 feet an individual swam directly towards me. I paused, breathing slowly, and waited. It continued to approach. Merely inches from me, with a subtle twitch of its pectoral fin, it turned and our eyes met. I noticed things that I had never noticed before – texture and depth. Details in skin. Movement in the eye. We swam together at depth for what seemed like minutes; perhaps it was only a few seconds. In some amount of time, it turned again and glided away from me. Before I could feel the loss of such a special moment, a new shadow appeared above me. I turned my body around and lay facing upward, floating in blue space with my arms and legs outstretched. And yet I still was not as large as she. I felt so wonderfully small.

Mexico has denoted these waters as a marine reserve – the country’s largest. Other agencies have also recognised the significance of Revillagigedo. It is listed as a UNESCO World Heritage site and a biosphere reserve. The islands that comprise the archipelago are peaks of an underwater mountain range, birthed by tectonic plate movement millions of years ago. Over time, underwater volcanic activity built up this range and, eventually, four masses of land breached the surface: Socorro, San Benedicto, Clarión, and Roca Partida. Generally, the open sea is akin to a desert. A place like this is an oasis, in part due to its unique location: a mixing point for two currents. This convergence causes upwelling, a phenomenon that forces deep nutrient-rich water to the surface. As a result, the waters here are highly productive and plankton proliferate. This provides a foundation for the ecosystem.

We were nearing the end of our dive, ascending casually to our safety stop when I first saw them. Three dark shapes in the distance. I squinted, trying to make sense of what they were. After a few moments, it was clear. Dolphins were swimming rapidly towards the group. When they reached us, they slowed and closed in – circling and inspecting us. Their movements were energetic and acrobatic; they swerved and weaved effortlessly around us. It was hard to know where to look. We all remained still, frozen together in that sought after mutual awe. Within minutes, they disappeared across the reef. Fading, again, into dark shapes. We continued our ascent.

The smallest of the Revillagigedo Islands, Roca Partida, had the most dynamic conditions. The whitewash of waves pounding against rock was intensely visible, even from 100 feet deep. It was a sheer drop down from the surface. Stories of currents so strong people had to climb across the rock itself circulated the boat, but the conditions we met were a bit less dramatic. The current was strong, but manageable. It was here that I saw wild tuna for the first time. Truly massive and hydrodynamic, these creatures cut through water with exceptional speed and precision. The currents that we found so utterly exhausting were negligible to the tuna. As I struggled to stay in place, they moved fluidly around the water column, scouting their attack. They were feeding on surrounding baitfish, jetting quickly at the school, sending them into a tightly packed ball of protection. After a few frenetic moments amongst predator and prey, the tuna moved on.

We journeyed back to the lights, back towards water more heavily and directly influenced by humankind. To experience a place so wild, so isolated, and so protected is emotional – it speaks to potential. Our potential. A convergence of appreciation and understanding, just as critical as that of two currents mixing, is the foundation for meaningful action and change.