WHAKATANE — “Here, hang this around your neck, we’re nearly there,” says Keris Adams, handing out yellow gas masks to some 50 ship passengers. I’m starting to feel uneasy. It’s only a few kilometers to White Island, the only New Zealand isle with an active volcano.

Even from a distance the island has something mystical about it, with its thick clouds of smoke rising slowly into the blue sky. James Cook must have seen something similar when he saw the island — the first European to have done so — in 1769. He wrote in his log book that they named it White Island because from a distance it looked white. Cook didn’t realize it was a volcano.

The island is part of the Pacific Ring of Fire, a belt of volcanoes encircling the Pacific Ocean that stretches from New Zealand to Indonesia all the way over to Japan and runs along the West Coast of the United States. Most of the 150,000- to 200,000-year-old volcanoes are under water, but White Island and its two-kilometer diameter thrusts 321 meters (1,053 feet) up out of the sea.

Because the island has been in private hands since 1936, it can only be accessed by guided tour. The number of visitors is limited, and they arrive either by helicopter or boat.

Keris Adams, the woman handing out the gas masks, works as a tour guide for White Island Tours, the only operator that offers sea access to the island. From the town of Whakatane on the coastal mainland, it takes 90 minutes by boat to cover the 48 kilometers to the island. During the trip many dolphins and flying fish accompany the boat. Transfer from the boot to the island happens via a rubber dinghy.

On the volcano

Upon arrival, we see a surreal, moon-like and downright dangerous landscape. Helmets and sturdy shoes are required. “You don’t have to wear the gas masks, but if you start having trouble breathing, then put them on,” Adams warns the visitors.

The high levels of carbon dioxide in the air can cause coughing attacks. It’s not dangerous or unhealthy per se, but it is an uncomfortable annoyance. Adams tells the tour group to stay behind her. “The hills that you see all around you are hollow on the inside, and if you fall through you’ll end up in hot mud.”

Hot mud? But before I can wrap my brain around this, Adams has us marching forth. We pass grey rocks and reddish boulders. Not a single blade of grass grows in between. In some places, the ground is covered with a layer of yellow sulfur powder, while in others hot steam sizzles from the soil.

On the White Island — Photo: Lutramania.

You might think you were on the set of a Hollywood blockbuster about the end of the world — if only there weren’t that vile stench of sulfur. It smells like rotten eggs and burns your nose.

Purely theoretically, the ground beneath our feet could at any moment start to vibrate. White Island is currently on the lowest level — one — of the five alerts for volcanic activity. At level one, there are only slight but constant seismic disturbances. White Island is constantly monitored, 24 hours a day, 7 days a week.

New Zealand’s Institute of Geological and Nuclear Sciences has installed several seismometers and cameras here. The last big eruption was in 2000, but there have been many small eruptions since then. The last one, which produced mainly steam, was recorded in August 2013.

As we continue our tour, I can see that the volcano is really very active. Pools of mud simmer and blubber, and hot streams flow across the island. The closer you get to the crater, the more steam escapes from the ground. These openings are called fumaroles. The temperature of the gases can reach up to 300° Celsius (572° Fahrenheit).

The crater lake is barely visible because of all the steam. There is a constant stream of thick, white clouds. I take my gas mask off briefly and am immediately overcome by a coughing fit. The steam burns my eyes. No wonder. “The water is so acidic,” Adams tells us, “that we would just dissolve if we fell in.”

Other parts of White Island are less toxic. Adams gives the members of the group a piece of sulfur crystal to taste. It’s salty. “Now try the stream over here,” she says. The water has a bitter note, and tastes like iron. “The workers couldn’t drink it,” Adams says.

Because there were once workers on White Island. Since 1885, there have been periodic attempts to reduce the sulfur amounts here. “The workers didn’t have serious health problems,” Adams says, “but, for example, they had to brush their teeth three or four times a day because all the gases and vapors turned their teeth black.”

And then one day the inevitable happened: Ten workers lost their lives when the volcano erupted. The ruins of the factory buildings are the last stop on our tour. The sulfur has eaten away at them. “Even the air here is full of acid,” Adams says. “The fasteners and material of my trainers disintegrate within two months or less.”

The power of nature is palpable at all times on White Island — and even as a take-away. After all, my lips taste of sulfur, and my skin reeks of it. “That’s the only downside of my job,” Adams says laughing. “When I get home, I stink of sulfur. Not exactly sexy!”