Sam vs. the Volcano: Sam Cossman's journey 1,200 feet to a lake of lava

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A couple of days before Christmas, Sam Cossman balanced precariously on a rock face 800 feet above one of the world’s seven permanent lava lakes, in the Marum crater on Ambrym island, Vanuatu, in the South Pacific. Dark was falling, but the orange light from the 2,000-degree molten rock below lit up the crater around him like perpetual sunset. The ActSafe powered rope ascender that was supposed to lift him and his 70 pounds of gear back up to basecamp was leaking fuel. All he could do was hug tightly to the rock wall and wait for tools and a new tank of gas to be brought down to him. Then it began to rain.

The sulfur dioxide in the air turned each falling drop into burning acid, and within moments the trickle of water down the rock face was replaced by a torrent. The ground above was mostly bare rock, so rainstorms quickly triggered flash flooding. As the water ran down the side of the crater it brought with it a hailstorm of loose rocks, before plunging into the lava below. When it hit the molten rock, thick, choking plumes of acidic steam rose back upwards.

Two days earlier, on his first descent of this expedition, Cossman had been hit hard by a falling rock. He’d lost his grip on the rope and been momentarily dazed, but luckily it had left no more than a painful bruise near his right collarbone. This time he might not be quite so fortunate. What the f--- am I doing here? he thought.


In late August, Cossman, 33, an experienced climber, had joined a scientific expedition to Ambrym, and on the flight home had patched together a video of his experiences in the volcano. That video went viral on YouTube overnight, and soon he had Fox News and Good Morning America seeking him out, asking for more. If he was going to have one chance to turn his passion for adventure professional, he figured, this was it. So in November he took the risk; he walked away from his startup job in San Francisco and began plotting his return to the volcano.

[daily_cut]Cossman didn’t just want to check a box—after all, he’d already been to Ambrym once—but instead to bring Silicon Valley to the volcano. He planned to conduct research with the help of a volcanologist and a planetary scientist, to bring along the latest tech products he could get his hands on, and to use those to tell the story of the adventure to everyone who couldn’t come along. But he had just a couple thousand dollars in the bank. He needed help, so he pulled out his Bay Area contact list.

His main sponsor, Kenu, provided both funding and a protective phone case that would allow him to do the unthinkable and take his iPhone with him into the volcano. “No one,” Cossman says, “wants to drop their multi-hundred dollar device [into] the satanic washing machine of lava.” Drone maker DJI supplied quadcopters that could be used to accurately image the entire crater, and image-processing company Pix4D would then convert those images into a 3D model of the volcano. Textile company NEWTEX provided an aluminized heat suit that would allow Cossman to walk right to the edge of the lava lake, 50 feet above the molten rock, and ActSafe gave him the motorized ascenders needed to lift all the gear in and out of the crater. Finally, market research company Sensum lent him biometric sensors he could use to record his physical and emotional response to the entire experience.


Within a month of leaving Vanuatu, Cossman boarded the return flight. With him were photographer and experienced volcano explorer Brad Ambrose, videographer Conor Toumarkine, drone pilot Simon Jardine, and geologist Jeff Marlow. Three days later they flew to Ambrym by helicopter and established basecamp a six-minute walk from the lip of the volcano. Over the next three weeks, Cossman descended into the crater three times.

At basecamp the temperature was a comfortable 75 degrees, but at the edge, within sight of the lava below, it jumped into the 90s. By the halfway point, more than an hour into the descent, Cossman’s iPhone shut down in the 110-degree heat. Carrying all of his gear—cameras and scientific equipment, his heat-resistant suit packed up ready to be worn on the crater floor, and his motorized ascender for the return journey—and wearing goggles and a respirator, the rappel down was exhausting.

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explains. But in the toxic fumes “you have to keep your mask on. I actually took it down a couple times. I was trying to just gasp for air. But every time I would take it off I would choke.”

He tried simply to focus on the next milestone, the next few feet, and on making sure all of his electronic devices were still working. When he could take a short break he chugged water to try to stay hydrated.

At the bottom, out of view of the lake, the temperature reached 120 degrees. Tiny fragments of solidified lava called lapilli fell from the air. Compared to his previous expedition, the volcano was more active, the heat more intense. The lava lake would surge and send splashes of molten rock towards Cossman and his team.

“Walking up to the edge for the first time was extremely intimidating,” he says. “My heartbeat was so fast, it was racing.”

“You know what you’re seeing,” he explains, “but your mind’s having a hard time processing what it is, because it has nothing to compare it to.”


​Even a heat-resistant suit, facemask and a respirator couldn’t protect him fully from the lava. A direct hit from a molten lump of rock could still cause serious injury and third-degree burns, and Cossman held his breath as the respirator struggled to keep out the fumes. The ground was unstable and overhangs could collapse into the lake. His eyes burned in the toxic air, and the intense radiant heat began to melt through the facemask. After 20 seconds at the edge, he turned back.

On each descent, the team stayed down at the bottom for anywhere between 30 minutes and an hour. The scientific goals of the expedition included taking data that could be used to better assess the risk of eruptions, and to study how quickly life would colonize freshly formed volcanic rock. They took measurements and collected samples of solidified lava. Then they headed back up the wall. Seven or eight hours after first crossing the crater’s edge, they crawled back out to safety.


Cossman is just one of a handful of people to have climbed down to Marum’s lava lake, and he might also be one of the last. The earthquake triggered an eruption, and reports from the island indicate that the lake may no longer be there.

Thanks to his expedition, though, he won’t be the last to experience the inside of Marum. About the same time as that eruption, Cossman was giving a virtual tour of the volcano to three users online using the 3D model he helped create.

Now back in the safety of the Bay Area, Cossman is already looking for his next adventure. On his to-do list are treks to the north and south poles, dives to the bottom of the ocean, cave exploration, and even a journey to the edge of space. Wherever he goes, he wants to bring Silicon Valley with him, experimenting with the latest tech in the most extreme environments. It’s time to pull out that address book again.