To stand on the slopes of Kawah Ijen is to be surrounded by beauty. The lake in the volcano crater is a stunning turquoise green, and the surrounding landscape strikes you with its views across the sea. White plumes of what appears to be steam billow from vents in the rock, adding to the ethereal atmosphere of the place.

But looks can be deceptive. What seems like a tranquil pool is actually a 182 meters (597 ft) basin of sulfuric acid, and the clouds wafting above a toxic mix of sulfurous fumes. Despite its sublime beauty, this volcanic caldera is a place of fire and brimstone, as enchanting as it is deadly. No one knows this better than the men who come here daily to mine the toxic sulfur for which the volcano is famous.

Located in the East Java province of Indonesia, the Ijen volcano is part of a group of stratovolcanoes — volcanoes made up alternating layers of hardened lava, rock and ash. The caldera known as Kawah Ijen was formed about 3,500 years ago when three massive eruptions caused an area of about 25 kilometers (15.5 miles) to collapse into the volcano, creating the giant water-filled depression we see today.

This large caldera holds the world’s most acidic lake, roughly a kilometer wide. Beside it lie vents that spout the elemental sulfur mined here. Ceramic pipes stud the landscape, channeling the volcanic gases containing the sulfur. These pipes are cooled by water, which condenses the gases into pure, molten sulfur.

When the molten sulfur first emerges from the pipes it has a temperature of over 200°C (392°F) and is a deep, blood red color. As the sulfur cools down it begins to solidify into vivid yellow lumps. These lumps are what the miners then break down into manageable pieces, which they can transport down the volcano in wicker baskets.

The miners produce about 14 tons of sulfur a day, which is used in the manufacture of a variety of everyday items, including cosmetics, fertilizer and even wine. It is also an important ingredient in the sugar refinery process.

Despite the large amount mined from Kawah Ijen, volcanologists believe only 20 percent of the total sulfur available there is being extracted. So there is not much chance of the mine ever running out.

If there is any job on Earth that could be described as hellish, it’s sulfur mining on Kawah Ijen. Every day the miners’ work requires them to break up and haul heavy loads of solidified sulfur, once known as brimstone, through toxic gasses and over difficult terrain. All this is done with little in the way of protective clothing or equipment.

The miners carry their loads of sulfur in two baskets suspended over their shoulders by a pole. Since they are paid by the kilogram, there is a big incentive to carry as much as possible. Their loads can weigh anything from 75 kilograms (170 lb) to 90 kg (200 lb).

Once they have filled and positioned their baskets, the miners must make their way up out of the caldera. This is no easy task, as the trip covers a distance of 300 meters (984 ft) up a 45 to 60 degree slope, all while balancing an incredibly heavy load.

The entire trek down to the base of the volcano covers around 4 kilometers (2.5 miles) of rocky path, and the miners make it twice a day. It’s no surprise that accidents are frequent, as are bruised and damaged shoulders, backs and feet.

Another hazard of working in the volcanic caldera comes in the form of the sulfurous vapors that the miners, who generally cannot afford protective clothing or masks, inhale every day. Visitors to the area report feeling nausea and dizziness after just a few minutes in the fumes, which also irritate the eyes and make it hard to breathe. A TV crew even reported the gasses corroding their cameras and making them unusable.

As you would expect, the miners who must spend hours enveloped in this noxious mix of sulfur dioxide and hydrogen sulfide suffer a high rate of respiratory diseases. The fumes are so corrosive that given time, they will even eat through teeth. Occasionally, the vapors can be fatal, suddenly hissing out from cracks in the volcano to catch miners unaware. Seventy-four men have been killed in the last 40 years by these unexpected gas clouds.

Nobody would work under conditions such as these unless they had to, and the men who toil on the volcano are mostly driven there by the lack of other job choices. They receive the equivalent of 5 US dollars a day for their backbreaking labor, which may seem little to us but is twice the legal minimum salary in Indonesia. Yet it’s still a pittance for a job so hazardous that it brings the miner’s life expectancy down to an average of 40 years.

The type of mining done at Kawah Ijen has been rendered obsolete in developed nations, but it still continues in Indonesia. The last mines of this type outside Indonesia closed down at the end of the 19th century. These days, most sulfur production is a by-product of other industries, such as natural gas and petroleum. Sulfur mining still occurs in the Andes, but here the process is totally mechanized. However, there are currently no plans to stop mining at Kawah Ijen.

According to some geologists, the Ijen Volcano is not a hazard only for miners. They warn that millions of residents in the area may also be in danger of sulfur poisoning from the lake’s acidic waters. Scientists say water from the crater trickles down to mix with fresh water supplies, as researchers have found evidence of acidic contamination in local rivers and wells.

The health problems associated with acidic water consumption by humans include tooth and bone disease and a potentially shortened life expectancy. Residents around the volcano say they feel no adverse effects from the water and are not concerned by the acid levels. Yet whether this will continue to be the case in the future remains to be seen.

Not everyone who comes to Kawah Ijen is involved in sulfur mining — tourists are drawn to the site from all over the world, eager to experience this amazing volcano and its caldera. Although not as popular as other Indonesian tourist spots, more and more visitors arrive every year as knowledge of the acid volcano spreads.

Perhaps when these visitors return to their home countries, they will carry not only the memories of an exquisitely beautiful volcanic region, but also the plight of the miners who work there.

And maybe when enough people know about it, something will be done to improve the lives of those who labor in such a visually stunning yet deadly environment.