Kawah Ijen in East Java: two unique phenomena in one hike

It only takes an hour or two for a reasonably fit person to **climb **to the rim of Kawah Ijen, an active **caldera **in East Java. The views from the top are gorgeous, especially at sunrise, but the main rewards await you below, a 30-minute hike down a rocky path. Two of them, actually: the famous blue fire, rivulets of molten **sulfur **burning with a bright azure flame; and the pool of sulfuric acid filling the caldera, the largest acidic **lake **in the world. That's two unique geological phenomena in one hike - a pretty good deal!

Sulfur miners: a slow suicide job

You will see those wiry men pushing carts full of **yellow **rock past you as you ascend the mountain. They are **sulfur **collectors. Armed with steel bars, they work right next to the active solfatara, breaking off chunks of natural sulfur. Primitive gas masks - or, for many of them, simply a piece of wet cloth - provide poor protection against highly toxic **sulfur **oxide fumes. And then, once the cart or the basket is filled, they start their journey up the stony steps and down to the mining camp, halfway to the foot of the mountain, loaded with 50-70 kg of the **yellow **mineral. Two or three runs a day, seven days a week. After a few years of such labor, predictably, many miners develop chronic lung diseases that incapacitate or kill them. Now that **Kawah Ijen **is becoming a famous tourist destination, some of them are taking up new jobs as guides.

Shades of blue on yellow background

When it comes to Kawah Ijen, descriptions like "unique" or "once-in-a-lifetime" become, for a change, more than just bloated superlatives of **tourist **commercials. It is quite literally unique. The lake in the **caldera **has the greatest acidity of any natural bodies of water in the world - PH as low as 0.15 in the middle of the lake. In short, it's sulfuric acid strong enough to burn your body or eat through iron. Due to its acidic content and a significant amount of dissolved minerals, the **lake **has a color of lapis lazuli. The rocks surrounding it range from Technicolor **yellow **of pure sulfur to reddish-brown of various oxides, producing an otherworldly landscape. Again, quite literally - that's what a similar but younger, less seismically stable planet might look like.

The blue fire

The other **unique **attraction is the famous blue fire, a **phenomenon **that can only be observed in Kawah Ijen. Sulfuric gases, mainly hydrogen sulfide, ignite upon contact with atmospheric oxygen. The **flames **are invisible in daylight, but at night one can see whole areas of rock burning with bright neon-blue fire. Flowing molten **sulfur **keeps emitting gas, and if the weather is dry, branching streams of **fire **spread from the **solfatara **towards the lake.

Getting there

The **climb **to **Kawah Ijen caldera **begins at Pos Paltuding. There's no public transport to that point - one can take a minibus from Banyuwangi in East Java as far as Licin village, then hitchhike the rest of the way. Walking from Licin would leave you winded before you even start the real **hike **- it's steep ascent all the way. Another alternative is to ride a motorbike, or, finally, take a local tour. Almost every guesthouse in Banyuwangi organizes those, and the program essentially consists of a rusty minivan getting you to Pos Paltuding and back.

Other practicalities

A few years ago **Kawah Ijen **has been officially declared a prime **tourist **attraction of East Java, and an entrance fee (~8$ at the time of research) has been introduced. Officially, the visiting hours start at 01:00 AM - yes, **one **o'clock; it's sightseeing for the night owls. Here's the catch: to see the two unique phenomena properly, you need to be there at different times of the day. The **lake **looks best in the early morning, while the **blue fire **is only visible at night. The most rational plan is to **hike **up the **mountain **in the middle of the night and stay for the sunrise. If you take a tour, make sure it lasts long enough to experience both. Pack sufficient drinking water, as any liquid you find in **Kawah Ijen **is poisonous. Gas masks can be rented at the entrance down below - take one if you intend to venture close to the blue fire. And, in any case, keep a safe distance; the **flames **reach 600°C, and a sudden burst of sulfuric gases can cover a wide area around the solfatara, creating a threat of suffocation. So long as you stay on the trail, the risk is negligible.