Few sights are as breathtaking as the sudden appearance of Gunung Rinjani's main crater at the end of the first day of this walk. Add in the even more astounding view from the volcano's summit and the serene beauty of being in the crater itself, and you've got a world-class trek that I can't recommend enough.
When I walked into Rinjani back in 1997 the local tourist industry was fairly basic, but things were obviously getting more and more sophisticated; I'm sure things are a lot more advanced now. I rented camping gear in the small village of Senaru and made my way into Rinjani on my own with nothing but a hand-drawn map for company, but even then some enterprising companies were offering all-inclusive packages complete with food, porters and transport. It all depends on what you want to pay for, but one thing's for sure: whatever you pay, the views will be exactly the same.
This isn't an easy walk, especially the last stretch up to the summit; the scree is exhausting to walk on and if you want to catch the incredible sunset from the top you have to start walking in the middle of the night. The summit is optional, but if you can manage it, you won't regret it.
There are two things to bear in mind when walking in Rinjani. The first is to make sure you carry out everything that you carry in, because when I was there the volcano was suffering badly from discarded non-biodegradable rubbish; only by keeping all your bits and bobs can Rinjani survive in its natural state. The other thing to bear in mind is that this Rinjani is in a remote part of Lombok, so take a decent first aid kit in case you cut yourself or get attacked by a monkey (hey, it happened to me!). Most people seem to forget things like plasters and antiseptic cream, but if you've ever grazed your knee on volcanic scree, you'll know what I mean.
Don't let me put you off, though. This is an incredible walk, and once you've seen that view from the crater rim, you'll see why. Enjoy!