Mount Rinjani (3, 726 meters)

In Geological curiosities, Hot springs, Indonesia, Mountains, Natural history, Treks and long walks, Waterfalls, Wild Hot Springs by Richard0 Comments


The view into the caldera from the crater rim on the Senaru side


The active cone inside the crater


Walking out of the caldera towards the campsite on day 3


Mount Rinjani, on the Indonesian island of Lombok (the island directly to the east of Bali) is one of the ‘big three’ trekking summits of east Asia (the other two being Yushan (3,952 meters) in Taiwan and Mount Kinabalu (4,095 meters) in Malaysian Borneo; Mount Fuji (3,776 meters) is sometimes added as a fourth). Like those mountains, it’s a compulsory challenge for all hikers spending any time in the region.

Although the lowest of the four peaks, Mount Rinjani has a good claim to being called the most magnificent. Catch some clear weather for the summit day, and the view of the caldera, the huge lake of gleaming blue water  (200 meters deep!) inside it, and the ominous, steaming, active cone of Gunung Barujari, (which has erupted several times in recent years, the last time in November 2015) is unequaled.

In terms of difficulty, Rinjani is a bit less strenuous than Kinabalu, but a longer, significantly more challenging prospect than either Yushan or Fuji. The hardest part of the climb is actually the descent, since the dry volcanic ash that covers the upper slopes of the volcano are treacherously crumbly underfoot, and the first couple of hours of descent, whichever way you go down, are a constant battle not to slip over painfully on your butt. A walking pole (preferably two) is probably as essential a piece of gear as good hiking shoes, warm clothes and tent on this mountain!

A map of the route, with Senaru, where we started) bottom right, the summit top middle, and Sembalun, the end of the trek) center left

There are three main routes up Rinjani, and apparently a couple of other rarely used ones too. The two most popular start at the villages of Senaru (600 meters) and Sembalun (1,150 meters); a third, the Torean Route, starts at the village of that name and is rumored to be more beautiful than the two better-known trails, but also more strenuous and, it is said, risky. A fourth route, starting at Aik Berik, round the far side of the mountain, opened in early 2017. On our visit (in May 2016), most hikers were starting the climb at Sembalun, summiting and descending to Senaru. Just to be different, we hiked the opposite way, starting in Senaru. It’s certainly the nicer, more interesting ascent route, through thick forest much of the way, but with 500 meters of extra vertical ascent.

We stayed a night in both Senaru and Sembalun either side of the climb, and much preferred Senaru, for the two brilliant waterfalls just a short walk off the road, and for the great resort near the waterfall trailhead (sadly we didn’t stay there) with an infinity pool looking out over the gorge below the falls.

The lower of the two waterfalls at Senaru, Air Terjun Sindang Gila


…and the much more amazing fall, Air Terjun Tiu Kelep, upstream

Before starting the trek, (or before heading down the mountain if starting from Sembalun), be sure to visit the two waterfalls just below Senaru. A fee is charged at the small small kiosk beside the trailhead; it’s apparently also possible to get in for free by following the water channel that joins the road quite a bit further downhill. The main trail heads down steps, crosses this water channel, and drops a bit more to the foot of the beautiful lower waterfall, where a tributary stream plunges over the cliff into the main stream. The second waterfall takes a bit more effort to reach (and you’ll get wet feet), but is the finest of the two by miles. To get there follow the water channel (through a short tunnel hewn out of the rock!), and on upstream until it rejoins the stream, then follow it up (you’ll have to walk in the water, as there’s no path for the last bit) to the foot of the magnificent waterfall, plunging in multiple jets into a huge pool.

The Trek: from Senaru to the Crater Rim

From the hotel/hostel area at Senaru (the Rinjani Trek Center is also here), it’s a short ride uphill to the start of the trail, which wanders gently through the forest to the true trailhead (marked by a gate, with a building beside it where trekkers sign in).

The group at the official trailhead above Senaru

From here the trail climbs steadily through the  thick forest to the first shelter, Pos II (1,500 meters) nothing more than a corrugated iron-roofed rain shelter in a jungle clearing. From here to the next campsite, Pos III (2,000 meters) the climb, still through thick forest, in places up ‘steps’ provided by the roots of huge trees, is a bit steeper. Monkeys with long grey beards like old men haunt these woods, and show little fear of trekkers: they’re obviously accustomed to seeing us as a source of food from the scraps we provide them (either intentionally or not).

On the trail near Pos II

Pos III lies near the tree line. It’s a scrappy campsite, and makes for a a short day’s climb if you stop here, but we’d got caught in a torrential downpour at Pos II, which turned the trail from there on upwards into a cascading stream, and most of us were happy to call it day.

From Pos III to the edge of the crater is about ninety minutes’ steep climb further. The forest immediately gives way to rough scrub, and the surface underfoot turns to tiny smooth spheres of volcanic ash or pumice which are very unstable underfoot. Going up is OK, but on the descent this stuff is treacherous, and it’s exhausting trying not to slip and fall heavily backwards. Most hikers end up walking on the vegetation at the verge of the trail, which is entirely understandable, but kills the plants, and is eroding the trail into a wide, dusty track.

For the final push to  the rim of the crater, the trail splits into numerous strands, each reaching the crater rim at a different place. Keep to the right, pass through the large camping area (which will be dotted with countless tents in climbing season), and just beyond it is the main viewpoint over the caldera, the crater lake, and the true summit  of Rinjani beyond. I’m not even going to try and describe the magnificence of the view. Just pray for clear weather, because on a clear blue-sky day like we had, it’ll leave you speechless.

The crater rim view





Down into the caldera and up the far side

The trail down into the caldera dives into it right in front of the viewpoint and campsite. After a short, steep section, the trail gets a bit easier, contouring the precipitous side of the caldera, gradually descending. The descent takes a lot longer than it first appears, and the later part of the walk is less interesting, with an endless descent through trees down a gentler section of the caldera wall, before the trail finally reaches the bank of Segara Anak (the mesmerizing crater lake) just before reaching the hot springs campsite.

View of Gunang Baru (Barujari)  from near the hot springs campsite

The lake and crater, which looked so spectacular from above, also look less amazing at first from water level, but approaching the campsite, the evil-looking steaming cone of Gunung Barujari commands attention. One of the great scourges of Rinjani, the masses of trash left behind by trekking companies, will probably have already made its presence felt, but be prepared: around the flat grassy, lakeside area of the hot springs campsite and along the shores of the lake, the trash problem is quite horrendous. The resident monkeys often end up chewing at it, which must be detrimental to their health.

The scalding hot-water stream near the campsite on day 2


Aik Kalak hot spring waterfall and pool

Three-day treks make a short break here (perhaps for the hot spring), then climb up the far side of the caldera to spend the second night back on the crater rim, but it’s well worth shortening day two and enjoying the amazing hot springs nearby at leisure. The high, sheer-sided rim of the caldera has broken through at this point, and several trails wander away from the lake, shortly joining an amazing stream of scalding hot water (don’t try and paddle or wash here!), and following its left bank down to a hot-water waterfall that plunges into a deep pool of bath-hot water. The pool is a perfect place to spend an hour or two, easing the aches of the long climb. Watch out though – locals seem to be in the habit of using the stream as a toilet  – a couple of our group caught a local man defecating beside the stream just above the waterfall and washing his behind with the hot water!  Immediately below the waterfall and plunge pool, the hot-spring stream plunges over a much higher waterfall, which is unfortunately tricky to see properly. Fragments of path lead downstream, but there’s a tricky rock face to climb down to get to the foot of the high waterfall. The Torean Route starts (or ends) at the hot springs. At least one tour company seems to offer this route to trekkers, although we heard that Rinjani National Park discourages foreign hikers from taking this way because it’s ‘risky’ or even ‘dangerous.’

Climbing out of the caldera en route to Pelawangan II campsite on day 3

After spending the second night in the campsite just above the hot springs, the third day is another short, but very spectacular one, as a trail from the campsite climbs the grassy hillside away from the lake. There are marvelous views back through the gap in the caldera wall to the expanse of blue, then later the lake is temporarily left far behind behind as the trail, first contouring the steep, grassy side of the volcano, zigzags up the seemingly insurmountable cliffs above. It’s an easier climb than it looks at first, and the few rocky pitches are simple enough even with a heavy-ish backpack, and by early afternoon the trail suddenly pops out at the top of the cliffs on the thin grassy ridge that serves as Pelawangan II campsite, where trekkers spend the night (the third and last, if coming from Senaru, as we did) before making an attempt on the summit the following morning.

The view from Pelawangan II campsite other the caldera and Segara Anak is stupendous in clear weather

By the time we arrived, around mid afternoon, the weather had already turned, and we were swathed in thick mist,  so that day we saw none of the amazing view back into the caldera and up to the true summit of Rinjani that the campsite affords in clear weather. However as sunset drew close, the mist magically cleared, and the long summit ridge above us slowly appeared, and (banded by a beautiful rainbow) the protruding summit of Rinjani at the end.

The summit of Rinjani from Pelawangan II campsite, at sunset

Sunset at the campsite 

To the summit

Most hikers start several hours before sunrise to reach the top at dawn, which often has the clearest weather of the day. It’s a notoriously strenuous 3-hour slog, but is probably easier in the dark when you can concentrate on putting one foot in front of the other without having to see the long, ever-steeper ridge covered in lose volcanic ash stretching far ahead. The steepest bits are the first and last sections. From the campsite, the trail climbs straight up the steep face of the crater rim, and its a frustratingly slip-slide-ey start to the long climb.  It’s about an hour to the top of the first steep ascent, when (if you’re lazy and you start after sunrise), the caldera, lake and steaming volcano inside will all come spectacularly into view. Assuming it’s still dark, that enormous pleasure will be reserved for the descent. This is one of the highest parts of the caldera rim, and from here onwards the ascent is very gentle for a spell, before it begins steepening as it starts the last, punishing push to the true summit.

The final push to the summit is a tough slog up lose volcanic gravel (photo taken on the descent)

The last hour or so is a hard, slow trudge up deep volcanic gravel, which makes the going slow and sore, especially if you’ve started late and can see the line of other headlamps way, way above you in front. You’ll know you’re nearly there when the way becomes rocky and there’s a tricky (when exhausted, as you will be, by now) little rocky step to haul yourself up. Get over this and the compact little summit is just a couple of minutes further. Most hikers arriving before dawn shelter in the lee of the rocks just below the top until the sun is about to break, as it’s freezing cold up here, especially if the wind is blowing!

Just before sunrise on the summit

At the summit!

It’s well worth making the summit, or at least climbing the first hour above Pelawangan II campsite to gain the high caldera rim, for the superlative views, which beat hands down (and then some) anything you’ll see from Yushan, Kinabalu or Fuji.



Gunung Baru from the summit trail

On the descent, the gravel is deep enough for confident trekkers to jog down, feet sinking far enough into the dusty mass to prevent slipping. Take care though – there are a few areas of thinly covered, smooth rock, which give little traction.


Down to Sembalun

Safely back down at the campsite (the final steep push down to it from the high crater rim is again treacherously crumbly in places), there’s time for a quick rest before breaking camp and starting the long, dull trudge down to Sembalun. The trail follows the line of the ridge past the several hundred meter-long line of tents in the campsite, then veers right down the far side of the volcano (not immediately obvious, so ask), and begins the one really unpleasant part of the whole trek. The first hour or so of descent is quite steep, and really crumbly, and it’s quite a feat to make it down without a painful slide onto the butt. Even though its very eco-unfriendly, we ended up walking on the vegetation at the fringe of the trail, to gain a bit of traction.

The later part of the descent to Sembalun on day 4 is a gentle but rather monotonous walk across a huge area of  rough grassland

Finally the steep downhill drudge softens out and the walking is easier. The dense jungle of the ascent from Senaru is replaced on the descent by rough grassland dotted with trees. There are a couple of shelters on the way that provide an excuse to break the monotony of the walk, and a few minor spots of interest, including several attractively rocky stream gorges. Just below below the last of these is a waterfall that might be worth seeing if it were easier to reach.

Immediately after the bridge across the stream just above this waterfall, our guides took us off the main trail and we went cross-country, along a series of tiny farmers’ trails, crossing several deep little gorges, before, after an hour or more, abruptly joining a road where a small truck was waiting to take us to our lodgings for the night. The trek was over!



Rinjani is best climbed in the dry season, from April to November. The routes are closed to all trekkers during the wettest months, January to March. We booked a package with a locally-based travel agency, and got an amazing deal for a nine-day package that not only included the 4-day Rinjani trek, but also took us from Surabaya, Java, with visits to Mount Bromo and the Ijen Plateau, across Bali (via Ubud for two blissful nights) and on to Lombok, finishing at Lombok airport after the trek. These packages (transport, accommodation and the Rinjani trek) can be amazingly cheap, and are a great way to see a lot on a short time, but they’ve received a lot of bad reviews from travelers, perhaps because they expect too much (accommodation on our trip was very basic). Guides are strongly recommended by Rinjani National Park, but apparently aren’t absolutely essential. Porters are well worth investing in though, as they’ll walk ahead, put up the tents and cook dinner for you, and act as guides, preventing any tension with park officials when signing in.  Apparently D.I.Y- ers can pick up camping gear etc in Senaru and Sembalun, although it would surely be safer to bring your own, along with food and other supplies for the trip – we saw little for sale on our day in Senaru.

The trek to the summit and back usually takes four days, although especially fit walkers can shorten the length to three days by combining days 2 and 3 (certainly possible as both are short, although a shame, considering how nice an afternoon at the hot springs is). If you don’t want to summit, a two day trip to the crater rim above either Senaru or Sembalun is a good compromise.

Trek over – heading for a shower at our hostel in Sembalun!


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