Pete Loud wrote:
[..]
Take a bus or minibus up to Ancak then a minibus to Senaru and
arrange it there. There will be guys hanging around who want to be
your guide. I think that there is a time in the year when lots of
the locals have a walk to the lake so it shouldn't be too difficult
to find a guide who is not too expensive. What might be best is to
meet up with another couple of tourist guys and go up without a
guide.

You could also start in Sembalun. You will find there a group of "Park
Rangers" who will also guide you or look out for a guide for you. Their
place is very easy to find (an as far as I remember also mentioned in
Lonely Planet). You could also ask only for a porter, those guys know
the way, but mostly no english ... they charge less ... it makes sens to
have a proter or guide since those guys know where to find water. They
will also help you in renting a tent and sleeping bag ...

What is it you want to do? Do you want to climb to the summit of
Rinjani? A more interesting walk is to the lake in the caldera.
Or a
walk just up to the crater rim is pretty good. I reckon the view from
the crate rim is the best panorama I saw in Indonesia.

You have not been to the summt, right? The view from the rim is good,
the one from the summit is much better! You need to be up there in early
morning, best for sunrise. The climb to the summit is rather tough,
because of the loose ground (two steps up, sliding 1,5 back) but
defenitely worth it! Bring a good torch!

There may a route to the summit from the east but I haven't tried
that.

You could also climb from Tetebatu, but I'm not sure if the trail to the
summit is usable now. If you're unlucky you end up at the rim without
any chance to go down to the lake nor to the summit. There is also a
trail through the jungle from "aik niet" (sesaot). The climb is very
long, I remember 3 days in the forest, one day up in the mountain until
we reached the rim .. very nice, but only few people know it, means you
need to get in contact to those people and since it takes rather long it
costs more (but is then real jungle trekking ;-))

I turned up in Senaru just after New Year, several years ago, I had a
night in Senaru then after breakfast I decided to rent a sleeping bag
from the losmen then walked up to the crater rim alone. I didn't
bother with a guide, I just followed the path.

The path is easy to find, the problem is water (as you mention later)

[..] I had very good weather, but I suspect that I was lucky. In
October there may be rain.

Raining season strts in mid october ... you can still be lucky but with
hard rain it can get very unpleasant up there

[..]

I suspect that the walk to the lake is the best walk, although the
path down is very steep and can be a bit dangerous.
The path down there is steep but without rain it is OK. If you're used
to standard mountain trekking it should be no problem. Staing overnight
at the lake is no bad. You can swim in the lake (fresh!) or enjoy
yourself in the hot pools from the nerby river with thermal water ...
Climinb the summit from the lake takes approx 6-8h ...

Manfred