When dawn had broken that day across the North Island’s north shore, before the light hit the beaches or the green mountains beyond, it caught White Island’s willowy plume, like a distant smoke signal, way out on the northern horizon. By the time Hayden Marshall-Inman arrived on Whakatane’s river-side quay to help prep the boat, the day was already sharp enough to give him a clear view across the Bay of Plenty, through the collapsed crater wall, and into the heart of the volcano. In his 40 years, Hayden had never tired of watching the steam shoot from the ground, puffing, balling, and rising into the wind before it drifted off across the water. The log he kept of his visits told him that this would be his 1,111th trip into New Zealand’s most active volcano, which followed 300 by his father, Alan, 69, a White Island Tours guide before him. When people asked, father and son always said: because it was never the same place twice.

The Marshall-Inmans shared their obsession with the Maori, to whom the island was a living ancestor, Whakaari, and the two dozen skippers, guides, and game-fish captains who drank at the Sportfishing Club, a few steps back from the wharf. Eight hundred years earlier, some of the first Maori to reach New Zealand from Polynesia came ashore at Whakatane. After James Cook’s arrival in 1769, the settlement became a town of shipbuilders, fishermen, and traders. By the 21st century, most of the men and women who still worked on the sea made their living taking some 20,000 tourists a year to the island.

The foundation of their business was an accident of nature that made White Island one of the world’s most accessible volcanos. With only a third of the cone above the ocean’s surface, and its fallen wall forming a giant natural drawbridge, all it took was 90 minutes in a boat or 20 in a helicopter and you were stepping off directly into the caldera. The place had a definite menace to it: the acrid air, the gas jets heated to 1,200 degrees, a lake at the bottom of an inner depression whose acidity was off the pH scale, and an abandoned sulfur mine from which ten men were swept away by a mud avalanche in 1914, leaving only a cat named Peter as witness to their final moments. Claude Sarich, who worked the mine in the early 1930s, wrote: “The worst hell on earth, a place where rocks exploded in the intense heat, where … [clothes] just fell apart in a couple of hours, where [men] had to clean their teeth at least three times a day because their teeth went black.”

The mine closed in the 1930s, and for decades White Island was largely forgotten. But in the early 1990s, as adventure tourism took off, Whakatane’s sailors and pilots began offering day trips to this other world across the sea. The thousand-foot-high crater walls, the raw rockscape, the fine dust—the whole power and wonder of it—was as close as most would come to walking on the moon. Hayden’s brother, Mark, who proposed to his wife, Andy, in the crater, described it as “a thing of beauty.” Add in the chance to sail between three rock stacks said to be the gates to the Maori underworld and you had an experience that the guidebooks called unmissable.

In the weeks that followed the eruption, hundreds of columnists and radio hosts would take a different view: How crazy did you have to be, they would ask, to go walking around a live volcano, let alone run a business taking people there? The truth was: not crazy at all. Compared with climbing or jet-boating, or even swimming or driving a car, visiting a volcano was safe. A 2017 Journal of Applied Volcanology survey of every recorded volcano fatality for the past five centuries found that an average of one tourist, climber, camper, student, pilgrim, or park warden died every year on a volcano. Instead, like earthquakes and tsunamis, most volcano deaths occur among people who live in the area—the Journal counted 800 million residents within 60 miles of the world’s 1,508 active volcanoes, and reported that 216,035 had died in 517 years—though today, with early warnings and evacuation drills, years can pass without a single one of those, either.

White Island was also one of the world’s most closely observed craters, studded with webcams, seismometers, UV spectrometers, and survey pegs. The chemical makeup of its air and waters was regularly tested. The results fed into a frequent analysis by the geological monitoring service, GeoNet, which rated the alert level on a scale of 0 to 5. Limiting tours to levels 1 and 2, and granting skippers and pilots the prerogative to cancel a landing if they didn’t like the conditions, had helped ensure no fatalities in more than a century, even though White Island erupted continuously from 1975 to 2000.

Visiting White Island was about the thrill of feeling a little more alive by feeling a little closer to death, all the while knowing that, really, you were in no more danger than you would be crossing a road.

That spotless record partly reflected the tameness of the tours. If New Zealand’s adventure industry often seemed like a marriage of the outdoors and mad science—seeing what happened, say, if you leapt off a bridge with a rubber band tied to your ankles—a walk around White Island was one of its gentler offerings. The crater was two-thirds of a mile in diameter; the walk covered about half that. The established route started at a jetty on the island’s southern shore and climbed leisurely up a dirt track through the collapsed crater wall, skirting bubbling mud puddles and steaming fumaroles before reaching the rim of the inner depression, from where visitors could gaze down at the acid lake. After that, it was a 30-minute stroll back past the old sulfur factory to the jetty. Tourists aged eight to eighty, wearing hard hats and carrying gas masks, had no trouble completing the trail in an hour and a half.

If White Island Tours was guilty of anything, it was of hamming up the risk. A leaflet from 2006 was headlined: “Volcano. Handle With Scare!” Guides liked to warn visitors that an eruption could happen at any moment, and that anybody caught in one could expect to be hit by rocks, scalded by steam, and enveloped in an acid mist as the crater lake flash-vaporized. Alan Marshall-Inman would have his groups dip their fingers in the coppery streams and ask them if they tasted blood. Hayden would tell the story of an ash eruption during a visit in September 2017. “We were walking into it,” he told a travel program in July 2018. “I could definitely feel the nerves inside me for sure.”

That was the whole idea of visiting White Island. It was about the thrill of feeling a little more alive by feeling a little closer to death, all the while knowing that, really, you were in no more danger than you would be crossing a road.