Is Kawah Ijen safe?

Is Kawah Ijen safe to visit?

Yes, for healthy visitors who stay on the rim with a guide. The park closes when conditions turn, and it has done so several times.

Ijen's alert level is I, normal, in October 2026, the lowest of four. When it rises, the crater shuts. Past closures show what the park reacts to:

After the February 2026 search, the conservation office reminded visitors that the official ticket includes insurance, that a licensed guide is strongly recommended, and that nobody should walk alone or split from their group.

How dangerous is the sulfur gas at Ijen?

It is the main hazard. Sulfur dioxide and hydrogen sulfide sting your eyes and throat and can overwhelm people with weak lungs, and the wind decides where the plume goes.

Most nights the gas rises from the vents on the crater floor and drifts over the lake. When the wind turns, it blows across the rim and the path. You will smell it, cough, and your eyes will water. A good guide watches the plume and moves the group.

Bad nights do happen. In March 2018, a gas surge sent 30 people to hospital and led to the evacuation of nearly 200 residents on the slopes (FMT / AFP). The advice experts gave when blue fire flared at Papandayan in 2026 applies here too: avoid hollows where gas pools, and leave at once if you feel dizzy or short of breath (iNews).

Do you need a gas mask at Ijen?

Yes. Bring or rent a proper half-face mask with twin filters. A cloth or surgical mask does almost nothing against sulfur gas.

The park lists a mask as required gear (park portal). Every tour on this site includes one. Fit it at the trailhead while you are calm, not on the rim in a gas cloud: the seal should press all round your face, and beards break it. Keep it on your neck, ready, and put it on the moment you smell sulfur.

Some miners work with only a cloth over their mouths. Don't copy them.

Gas mask, trekking pole, guide, entry and breakfast included, from Banyuwangi or Ubud.

★ 4.0 · 9 to 15 hours · from $38

Explore the Banyuwangi or Ubud tour → Tour details

Who should not hike Ijen?

People with heart disease, asthma, respiratory infections or breathing disorders, according to the park. Children under 7 can't join the most booked tour.

You need a health certificate issued no more than three days before your visit (park portal). Tours stop at a clinic on the way for a quick check. If the doctor says no, take it seriously: on 30 December 2023 a visitor from Jakarta died on the trail of a suspected heart attack, and the park closed for four days to tighten its health rules (Kompas).

Also think twice if you get vertigo near drops, are pregnant, or can't walk uphill for two hours. The all-inclusive hike sets its minimum age at 7.

Is it safe to go down to the blue fire?

It is the riskiest part of any Ijen visit, and the volcano agency advises against it. In 2026 it is often off limits anyway.

PVMBG's standing advice, repeated when it lowered Ijen to normal in August 2023, is not to descend toward the crater floor and not to stay within 500 m (ESDM). The path is loose rock in the dark, the gas is thickest near the vents, and you share the track with miners carrying 75 to 90 kg.

In October 2026 JawaPos reported a ban on approaching the blue fire (JawaPos). If your group does go down, stay with your guide, keep your mask on, and turn back if your eyes or chest burn. More in the blue fire guide and the descent update.

Can you swim in the Ijen crater?

No. The lake is sulfuric acid with a pH measured between about 0.1 and 0.5. It would burn your skin, and there is no path to the water for visitors.

The lake is about 1 km wide and 200 m deep, and it is the largest highly acidic crater lake in the world. A 2001 expedition measured a pH below 0.3; in 2008 explorer George Kourounis measured 0.5 at the edge and 0.13 in the middle (Wikipedia). Battery acid sits around 1.

Its colour, the turquoise everyone photographs, comes from the acid and the dissolved minerals. Admire it from the rim.

Is Ijen the most toxic volcano in the world?

There is no official ranking. Ijen holds the largest highly acidic crater lake on Earth and pours out sulfur gas daily, which is where the reputation comes from.

Toxic to whom matters. For visitors, the danger is short exposure to gas on the rim. For the miners, it is years of breathing it with little protection, and they report respiratory problems. For the land below, acidic, metal-rich water from the lake feeds the Banyupahit River and harms the ecosystem downstream (Wikipedia).

Is that the most toxic in the world? We won't claim it, and neither should a tour advert. It is toxic enough to plan around.

What is the deadliest volcano in Indonesia?

Tambora, whose 1815 eruption killed an estimated 92,000 people, mostly through the famine that followed. Ijen is nowhere near that list.

Indonesia holds the grim records. Estimates from Oregon State University's volcano pages, which stress they are best guesses (Oregon State):

At Ijen, the recorded deaths in recent years came from health problems and falls, not eruptions. In April 2024, a 31-year-old visitor fell about 75 m from the crater edge while posing for a sunrise photo (Mothership). Stay back from the edge, even for the picture.

Go with a guide who keeps the group together and away from the edge: the standard Ijen night, done properly.

★ 4.9 · 9 to 23 hours · from $15

Explore the all-inclusive Ijen hike → Tour details

Frequently asked questions