On 1 March, 1954, the US military detonated a 15-megaton thermonuclear device on Bikini Atoll, codenamed Castle Bravo. The 4.5-mile-diameter fireball, forming within one second of the blast, was visible on Kwajalein, 250 miles away.
The blast vaporised two Bikini islands, blew a crater 76m deep by 2000m wide into the atoll’s ring and formed a mushroom cloud reaching nearly nine miles into the sky.
As islanders through the archipelago reported “the Sun rising in the west”, contaminated residue from the cloud began dropping radioactive debris, up to 2cm deep, on Rongelap and its unprepared population, 95 miles east.
Sixty years, billions of dollars and decades of clean-up have now rendered Rongelap safe for human habitation again. A small population of Marshallese have repatriated Rongelap to re-establish an historic way of life, lost for so long.
Because it’s safe for the islanders, it was also safe for the Indies Surveyor to explore the passes, slopes, walls and reef crowns around the atoll.
Our crew had surveyed charts in advance for more than a dozen dive-sites, most unnamed, and many likely never to have seen a diver. And over the next five days we would shoot the rapids at passes on incoming tides, visit never-before-dived vertical walls and explore coral gardens that rival any in the world.
We arrived at Rongelap ahead of schedule. The seas were calm, and good juju resulted in a pair of large yellowfin tuna from handlines trolled behind the Surveyor, begging the question of which comes first – breakfast sashimi or diving? The tuna could wait.
We iced the catch, kitted up and rolled into impossible 50m visibility at 8am. We were greeted by grey reef, then silvertip sharks as we descended through 35m.
The quarter-moon phase generates a mild current, and we drifted across a beautiful spur-and-groove reef towards a distant pass. I was shooting wide-angle, but noted the 7cm Helfrichi dartfish hovering above small, sandy pockets on the slope, which was now near-vertical, at 30m. I saw too many fish that were new to me and my image library, so decided to shoot macro on the next dive.
Bottom-time and nitrox waning, I worked my way toward the crown of the slope, where the coral coverage was dense and diverse. Finally, I saw them. At 20m, in a wide sandy bowl, a pair of beaded anemones were hosting families of three-band anemonefish!
I had the wrong kit, but hoped to get a few shots by carefully placing the glass of the dome-port millimetres from the animals. It appeared to be a good omen; it was our first dive on the outer reef, and I had already found the underlying purpose for pulling this trip together.
As it happened, we later found that this reef was the only known location for the three-band anemonefish. After several additional days’ searching for the fish at other sites, the group was kind and agreed to return to this reef, allowing me to capture more images with my macro kit.
We finished our dive on a shallow corner of reef at the mouth of the pass, where the current had accelerated sharply due to the venturi effect created by the tidal bore pushing against the narrow, shallow pass opening.
We found sanctuary from the current in small amphitheatres below ridges of dense coral formations outside the pass, and lingered there photographing the many colourful fish.
Next morning we steamed to West Pass, a remote, deep, narrow channel between the lagoon, reef crown and open ocean on the western ring of the atoll.
No other passes lay nearby, and we expected a “shoot-the-rapids” dive experience on the incoming tide.
We were not disappointed. While the current was too strong for most reef-building corals, the walls were covered with orange-pastel sea life, coral-like in nature but unknown to all of us. As on all the other dive-sites on the outer reefs, the ubiquitous sharks followed curiously.
In 2016 the central Pacific, along with most of the world, experienced a significant, extended warmwater event that exacted a toll on the Marshall Islands coral population. By the time of our 2018 trip, unless you knew the tell-tale indicators of bleaching damage you’d believe that most of the sites we dived were minimally, if not completely, unaffected.
However, as we were exploring new sites every day, we expected and did come across two reefs heavily damaged and struggling to recover, as evidenced by the abundance of macro algae inhibiting new coral colonisation.
Yet most of the locations we dived were in excellent shape, well along the road to recovery, as measured by the numbers of fist-sized coral colonies established between older, larger growth colonies that had survived the warmwater event.
On the fourth day, we discovered something incredibly rare: a spectacular reef with the most dense, colourful and diverse coral coverage that any of us had witnessed anywhere in more than a decade. It was stunning!
Beginning with an open forest of table corals, many 2m in diameter, and building to an impenetrable plateau of hard corals, this reef surely set a gold standard in reef health. Everything was big, healthy and colourful, including a century-old giant clam. It left me hopeful that even under the deadly impact of recent climate-change-driven events, Mother Nature’s resilience can still surprise us.