Semeru or Mount Semeru (Indonesian: Gunung Semeru) is an active volcano in the Bromo-Tengger-Semeru National Park on the island of Java in Indonesia. Climbing Semeru is one of the best treks in Java. It is quite demanding, even though it requires no professional skills. The trail begins in the village of Ranu Pani, and can be completed in two days (this is the minimum).

Several travel agencies (mainly in Malang) offer to organize everything you need for the trip. However, you may very well go by yourself, from Malang to the top of the Semeru (and back!) Explaining how is the main purpose of this article.

Understand

Lake Ranu Kumbolo

Most people climb Mount Semeru in two days and one night. The first day is an easy but long walk in the forest via a lake (Ranu Kumbolo) until the Kalimati basecamp; the second day starts with the proper climb, before returning to Ranu Pani straight away (after taking breakfast in Kalimati). It is however possible to spend more days in the park. For instance, most Indonesians sleep twice in Kalimati. Other people stop at the lake on the way back to sleep there. The lake has really pretty surroundings.

The main interest of the whole thing double-sided: the view from the top at sunrise is breathtaking (your are one thousand meters above the Bromo caldeira); you are at the top of an active volcano, which erupts every 20 minutes or so (ash, gas and lava).

Prepare

• Office of Bromo Tengger Semeru National Park, Jl. Raden Intan No. 6, PO Box 54, Malang, East Java, ☏ +62 341 491828. If you intend to climb Mount Semeru (only for serious trekkers and often closed due to eruptive activity) you must apply for a permit in advance. 

It seems that access between stay of January and end of March is forbidden: no permit is possible.

Get in

From Malang two travel agencies organize tours to the Semeru in two days and one night. One can also ask for a three days and two nights package. These two agencies are Bromo Holidays Tour and Helios Tour. As of August 2018, the cost is Rp 3.5 million and Rp 3.05 million for one person in a group of two people, respectively. The price decreases with the size of the group. The tour begins at 05:00 and ends around 19:00 the next day.

Otherwise, the idea is to go to Tumpang ,and from there reach Ranu Pani. From Malang, you may take a bemo to Arjosari which is the bemo station (around Rp 5000). Then you will find another bemo to Tumpang. It takes roughly 30 minutes and will cost you around Rp 10,000. On Jalan Sadewa, the Tumpang Camp Adventure can organize the tour for you, give you precious advise, and book a jeep for you.

Tumpang is 1.5 hours away from Ranu Pani by jeep. The road is actually good, so one may take an ojek (motorbike taxi) as well. Most people find a jeep and a driver in Tumpang, the cost is typically between Rp 500,000 and Rp 1,000,000 per jeep. You might find cotravellers in town to share it.

The beginning of the trail is at a walking distance from Ranu Pani.

Hike

Day One

Frost in Ranu Pani

The walk from Ranu Pani to Kalimati takes around six hours. The gates of the National Park open at 08:00. The entrance costs about Rp 250,000 per person and per weekday, and about Rp 300,000 per person and per weekend day. Locals pay much less. The best is to arrive at Kalimati before sunset, to camp and have dinner before night comes - it gets very cold afterwards. The track is not difficult, almost never steep and not always going up. It can be slippery though. Along the way you find several Pos, where you may buy water, refreshments and snacks. There are three of them before the lake, which you reach in about 3 hours. Most people have lunch there. You can buy food there (including instant noodles).

Then, you have three hours left to reach Kalimati (this part is slightly more difficult), with two more Pos to go.

Day Two

Climbing the cone takes 4 hours; going down one; walking from Kalimati to the lake takes another hour; the last part takes the same time as the day before: 3 hours. In order to be at the top a bit before sunrise, you may start walking at 01:00. The first hour leads you through the forest, on a very steep path but at least a solid one. The three hours that follow are by far the most difficult. You will have to walk in lapilis (coarse-grained sand). Not to loose too much energy, it is better to have an efficient walking technique. At each foot step, basically shoot in the ground to dig a step, on which you will stand without sliding. Above all, don’t run and stop (like many do). The secret is to be patient: step by step you will make it eventually. Keep in mind the distance you have to walk in the ash is actually very short (ca 2 km), so even if you go very slowly you will make it in good time (3 hours). As a matter of fact, the more slowly you go, the more efficiently you go.

Mahameru summit of Mount Semeru

When you reach the summit, be careful. First, the temperature is very low, only a few degrees above 0°C. Don’t hesitate to take gloves and a hat in your bag. You can also bring you sleeping bag up there. Then, be very cautious of the crater. When you reach the top, it is still rather far away (a few hundred meters to the east). When the volcano explodes, you may see lava though. Then, you may get closer if you know what you are doing: rocks are emitted, as well as gas - don’t hesitate to ask the guides on the top for the latest info about the crater activity. After the sun rises, you will mainly see smoke out of it. In any case, leave the area before 10:00, because the wind changes direction.

The way down is a lot of fun and takes 1 hour to Kalimati, where you may take your breakfast. From Kembali to the lake, it is way shorter than the way up (1 hour), whereas the last part takes the same time than the way back. This is why it can be a good idea to spend more time at the lake before going down. It is forbidden to swim in the latter, since it is a source of water for the camp.

Eat

You will find little shops at every Pos along the way, that is to say three before the lake, one there, two along the way to Kalimati, and one last at the camp. They sell water bottles, instant noodles (and hot water), fresh fruits, fried bananas and tofu, tea, etc. Prices increase with the altitude: a water bottle at Kalimati is Rp 25000, compared to Rp 9000 in the valley. One portion noodles at the lake costs Rp 15,000.

Stay safe

Mount Semeru was at activity level III or alert in December 2021. There was a further eruption on 4 December 2022. You have to look for the recent situation of Mount Semeru before climbing it. It is advised to avoid the area during eruptions due to the ash and the lethal gases around the volcano.

Go next

• To the east, Lumajang regency.