Mount Rinjani is an active volcano located in Lombok that rises to 3,726 metres, making it the second highest volcano in Indonesia. Climbing to the Summit of the volcano was the hardest thing I did on my nine-months trip around Southeast Asia. The two day-one night hike from Senaru was a real challenge both physically and mentally, but the views from the crater rim and the summit were truly breathtaking and really worth the effort.
You can either start the trek from the villages of Senaru or Sembalun. I would recommend beggining at Sembalun as the starting point is already 1100 metres high while in Senaru starts at 600 metres high.
Most of the Indonesian trekers go without a guide carrying their own backpack while the mayority of the foreigners choose a guide tour including porters who will carry the tent, sleeping bag, cooking utensils and food. The negative part of the tours is that it feels very rushed and if you are not in good shape is very challenging to follow the itinerary. Most Indonesian trekers I spoke to hiked in 4 days the distance we did in only 2 days.
If you go for an organised trip and your priority is climbing to the Summit the best option is doing the 2 days one night trip, while if you want a more scenic view of the National Park the 3 day trek includes the lakes and the hotsprings.
There are lots of travel agencies in Bali, the Gilis and Lombok where you can buy the tour, however, ask the name of the company you will be doing the trek with and the conditions. You can also contact the guest houses at Sembalun and Senaru to arrange it directly with them.
The trekking company we went with was Rinjani Tropis which is the cheapest one: we bought the 2 day 1 night trek for 60€ each including a extra night of accomodation in Senaru, all the meals and transportation. Sadly, I wouldn´t recommend it. We were 12 people with only one guide and 6 porters. The food was basic fried rice, noodles, eggs and pancakes. The tents at the base camp were falling apart and the rain was coming through and we were only provided with a thin sleeping bag.
2 day 1 night tour from Sembalun. We started at 9am and had 2 stops at the Pos 1 and 3, and an hour lunch break at Pos 2. We reached the base camp just after 5pm and the views from the crater rim at sunset were absolutely stunning with a panoramic view of the lake. After a short and cold night sleeping in the tents, we were woken up at 2am to climb up the Summit before sunrise. This was definitely the hardest part of the trek both mentally and physically. It usually takes about 3 hours but in my case it took me 4. It was really freezing and windy and the path is very steep and slippery as you get closer to the Summit. The outstanding views from the top are the best reward to the hard work, a really magical sunrise.
Things I wish I brought to Rinjani: thermal clothing, a raincoat, trekking boots, globes, a hat, climbing sticks, a frontal light, protein/chocolate bars and electrolytes to add to the water.