Quite a few people have contacted me having read my blog and seen that I did this route in early 2010. I figured it would be helpful if I put my response on here.
It's quite detailed. Some people think that following in others' footsteps ruins the experience and goes against the spirit of overlanding, and if you're one of those folks, then this isn't for you. However, if you want to have a clear idea of what the route entails, read on.
The road is rough, and the going is slow. You may have issues with punctures if you don't have good quality tyres. Consider taking a couple of spare tyres if you can. Also, seriously consider trying to go in convoy. Not only will it be helpful if you get a puncture, get stuck or whatever, but it's also a lot safer and imo, more enjoyable (provided you have right travel buddies!)
When we went it was the safest route north, and we did in a convoy of 2 trucks and 2 cars. Whilst the road was really rough, it was also probably one of the highlights of the entire trip (which is no mean feat considering we travelled 40000kms over 19 months - so we saw a lot of things!!) and in fact we didn't feel threatened at any time. Once you're north of Maralal it gets really safe anyway.
It took us 7 days to get from Nairobi to the Omo Valley in south west Ethiopia, although one of those nights was spent with one of the trucks stuck in a river bed, so we could have taken 6 days. You could probably do it quicker if you don't have trucks, but it is a helluva rough road so going is slow.
Before you leave Nairobi get your carnet stamped because there is no customs at Illeret. Ask Chris at Jungle Junction to help you. (Please tell him Roxy and Steve say hi!)
Also, if you have any mechanical issues Chris has some awesome mechanics who can fix just about anything.
What you want to do is head north out of Nairobi to Nanyuki. It's good tar road. There's a Nakumatt which you can stock up at, and fill up your fuel tanks and jerry cans. Get a lot of fresh water - this will most likely be the last place you can get good clean water for a long time.
Head west on the C76 (what's locally called the old stock road) towards Rumuruti. It's a good quality dirt road, although there are sections with black cotton, so be careful if it's wet. Also if you're in a truck, be careful of the elephant gates, which are steel cables strung over the road with steel cables hanging down. It prevents elephants from crossing into farmland via the road, but can cause serious damage to higher profile vehicles if you drive through the cables at speed.
South of Maralal be relatively careful of where you camp if you bush camp, it's not that safe - lots of shiftas. Most violence is inter-tribal, but you can fall foul of opportunistic theft if you're exposed. It's much much safer than the Marsabit to Moyale route though.
We camped in the yard of a game farm run by some muzungu's, a white Kenyan Tom, his sister and her English husband Harry. They're all very friendly people, and were happy to let us camp overnight. We also drove past a police compound which I guess we could have camped in if we had asked.
Once you hit Rumuruti turn north onto the C77. This is a really shitty road, going will be slow, the road is really potholed. Head north to Kisima, and north to Maralal.
There is a fuel station at Maralal, but don't count on there being fuel available. If there is, fill your tanks. The road starts to get rocky and rough. Drop your tyre pressure somewhat to allow for some give going over the rocks. Obv. don't drop your pressure too far so that you expose your sidewalls to the rocks.
From Maralal continue north to Baragoi and South Horr. The road gets really rough, some very rocky and steep sections. Take it slowly.
We bush camped on an old abandoned farm about 100m off the road. There is loads of wood around (including old fence posts which are very convenient firewood!) so you can make a good fire. There aren't many people around, so it's safe (although try get far enough away from the road that you can't be seen from the road - no point in advertising your location)
In Baragoi there are another two fuel stations and a booze store - stock up if you can!!
Once you're north of Baragoi you start leaving civilisation behind you, things start to take on a lunar landscape appearance and you arrive at Lake Turkana. Head to Loyangalani, and stay at the Palm Shade campsite. It's one of the few with a bit of shade, and is a great little place. Be careful of scorpions around Lake Turkana. (apparently also be aware of crocs and vipers, although we didn't see any).
Leaving Lake Turkana's shores you head into the Chalbi Desert, a stony desert. The pace picks up. Awesome places to bush camp under Acacia trees in the desert.
You have to go through Sibiloi National Park, which is something like $20 (can't remember exactly) per person. Tell them you're only staying for 1 night, even if you end up staying longer - there is no exit gate. There is a map available but it's horribly out of date - roads on the map no longer exist in the park.
Head to Illiret, on the north side of the park. Find the police station and register your exit from Kenya with the police. They don't have a stamp or anything, but if you ask they will write a letter for you stating they have recorded your exit from Kenya, which you then give to the Ethiopian officials in Omorate when you stamp in.
There is a mission in Illiret with a nice Franciscan monk who will let you camp in their grounds. They are low on fresh water (they rely on rain water), but you may be able to get some from him if you need it.
North of Illiret it's really sandy and the track meanders all over the show, depending on when it last rained. There are a lot of river bed crossings, but it's not too bad. At some point you will cross an invisible line and arrive in Ethiopia! Yay!
You will get to a check point with a little hut. Register with the police if they're there, if not don't worry. You will eventually meet a dirt road going east/west. Turn left and drive to Omorate. There you will find immigration and customs where you will have to check in and get passport and carnet stamped. To get birr (local currency) go further into town and find the hotel. Ask around and you will be able to change dollars on the black market.
Now turn around and head out of Omorate the way you came in and get to Turmi which has a really nice little campsite called Kaesa Mango River Camp. You might be able to buy fuel from barrels if you ask around.
If you can, go to Jinka to see the Mursi people (lip disks). It's all a bit commercialised (you have to pay for a photo, but only like 1 or 2 birr per person) and gets a bit chaotic coz they all want the cash but it's an awesome experience. In Jinka we stayed at the Rock Campsite which is really good. There is a fuel station in Jinka - this is probably your first guaranteed chance of getting fuel since Nanyuki, so a good 600+ kms.
Hope this helps
Cheers
Steve
www.overafrica.org