Information
These are some various tips & opinions you might consider if you're planning a long hike in Iceland yourself, particularly through highlands in the middle of the country.
ICE-SAR
If you're planning a long trip in the Iceland backcountry (not including more well-traveled areas like Landmannalauger-ţórsmörk, or maybe the Askja route, etc), it is a really really good idea to register with the Iceland Search and Rescue before you go. It doesn't take long, doesn't cost anything, they're really cool, and it just might save your life. They have an office near the domestic Reykjavík airport... you just have to show up during regular business hours. They have a standard form to fill-out where you list your general itinerary, and emergency contacts. They'll then keep you on their "watch list". That only means they'll keep you in mind if a major storm blows in (and they're not busy with more pressing issues), or if they don't hear from you for some time after you should be done. They just ask that you check back with them (phone or e-mail) when you reach your destination. The whole process is very low-key. Just remember there are many places in the highlands far from roads, that may get only a couple visitors a year. If you break your ankle out there and are alone, it could easily be a death sentence. Even if you do register with ICE-SAR, they may not start looking for you until considerable time has passed, so it's hardly a great safety net. If you're traveling alone, or are concerned about safety, you might consider bringing an emergency transmitter with you. I don't have a lot of details on these, but it is common for people to carry them - so I guess there must be some lightweight varieties. These are similar to transmitters that fishing boats use. ICE-SAR monitors these frequencies and will be quick to act if you activate yours.
Maps, GPS, and Navigation
I'm usually of the opinion that more detail is better with respect to maps, and that GPS is generally not required for land-travel. However, Iceland proved me wrong on both accounts. There were a number of cases where I wished my maps had broader coverage, since the navigation points I was looking at were sometimes many miles away, and "off the edge of my map". The immediate detail could be very confusing since there was very little "scale reference" to the eye - it was difficult to tell how large or how far away various land features were. And in flat areas with very little geography, a detailed topo map is of little use. Additionally, my detailed maps were not as up-to-date with respect to man made things like "roads". I'd suggest sticking with the 1:100,000 series maps available from the Iceland Land Survey. They produce a CD-ROM that has all the 1:100,000 maps for the entire country. The trouble is that the software with the CD-ROM only prints to a maximum size of 9cm x 9cm - not very useful! If you want to print larger maps, you have to export screen shots to photoshop, and re-assemble them. I did this with the 1:50,000 maps, and it was a bit of a pain. You can also buy paper copies of the 1:100,000 scale maps, but these get expensive. There are a variety of other maps that cover certain areas at various scales, particularly for the Landmannalauger area. The GPS I brought really helped us out of a few binds. We'd have been quite lost at times without it. But, for maximum usefulness, you have to enter some "known waypoints" that are also marked on your maps before you go. It's a good idea to mark a number of these for things like huts, intersections, or stream crossings, etc. The 1:100,000 CD-ROM software is helpful for this. Be sure you're very familiar with the operation of your GPS before you go. I only turned mine on when I needed it, so that saved on batteries. With no trees, it only takes seconds for even a wimpy GPS (like mine) to get a lock.
Footwear and "Route Tread"
Going through the highlands in late-June to July, I was fine with the same kind of lightweight low-top hikers I wore on the CDT. Ankle gaiters would have been very useful though - there is an immense amount of grit out there, and it's really nasty stuff to have in your shoes. With few plants to hold it down, it blows around when dry, and sticks to everything when wet. I can't count the number of times I had to stop to "empty" my shoes. Some people would probably be fine with full "running shoes", but that's never been my style - I like just a tad more toe protection and a little more robust sidewalls that don't blow holes so easily. Nearly all the Europeans we saw wore massive hiking boots and probably thought we were crazy with our little shoes. Oh well. Generally, the terrain underfoot was really good - mostly rather firm sand or tundra. There were a few tussocky areas (mostly in the north), but these weren't too severe. The route passed over a few areas of steep gravely hardpan, where stiff boots would have been helpful. There were some snowbanks, but most areas had melted-out by late-June, and the snowbanks were mostly well-consolidated, brief, and not steep. Then there was lava, which was a whole other story. The lava flows varied quite a bit, but most were not easily traversable. If you have your heart set on heading cross-country over lava fields, don't expect to make quick progress. The ropey lava is certainly a lot easier than the spider lava, and older flows were mostly better than newer flows (older flows were more broken-down and partly covered with sand), but hiking any route over lava you're likely to encounter all types of it, and it will slow your progress to a crawl as you work your way through a maze. Generally your only choice in bad lava is to follow an F-road, or marked trail posts.
Roads
With any long route in Iceland, you're likely to be following some roads for part of the way, either to access a bridge over an un-fordable stream, or to help navigate over lava or otherwise confusing/difficult terrain. There are a variety of road "types", loosely identified by the type of number on the road. These are as follows:
1: This is the ring road, and is >95% paved.
Two digits (i.e. 12): About 50-75% of these are paved, and they tend to be well maintained.
Three digits (i.e. 123): About 25-50% of these are paved, and they tend to be still well maintained, but perhaps not quite as well-traveled as the two-digit roads.
F Roads (i.e. F123): These are not paved, and often not maintained. But, they are marked with posts at regular intervals. When you see the terrain some of these roads traverse (i.e. endless fields of sand), you'll understand why it makes no sense to pave or maintain them. F roads through lava fields are especially helpful. These are often blasted-through the lava, to make a consistent (though still circuitous) path.
Tracks: These are marked on many maps as parallel dotted lines, but with no number. These tracks are not maintained, and rarely marked. Often, they just indicate "the way", and as a result there may be multiple parallel tracks following "the way", not exactly where the map indicates (but close). The routes may shift over time as the terrain shifts, etc. Some of these even go over lava fields, but don't expect anything special - just a "way through" with a hopefully minimal amount of weaving around lava heaps. Often, you'll really have to look hard to figure out where the track goes.
Sandstorms
A good deal of the interior is made of gritty sand, often pulverized pumice. When this dries, and the wind picks up, it can get lifted right off the ground, and makes for a significant obstacle. In some places, there is just no shelter to take. My experience with sand storms is limited. We only had one bad day with these, and they tended to be gusty, so we could hunker down for a few moments, then proceed for 30 seconds, then hunker down again... The gusts were indeed "man stopping", as these storms are often described. I was knocked back on a number of occasions. I'm not sure I have any good advice if you're caught in a severe prolonged sandstorm with no cover for miles around. One important piece of advice is to bring some sunglasses with a good "wrap-around", to help keep the sand out of your eyes. I had some, but still got sand in my eyes - and that ain't fun. I would have been really screwed without them however.
Stream Crossings
Something like 1/10 of Iceland is covered in ice, and it's all melting, all the time. There are thousands of streams all over the place, and there is simply no way to have bridges over most of these streams. Like any streams, if you're sticking close to the "sources" of the streams, you'll tend to have better luck - before the stream has a chance to gather into an unfordable single channel. Another idea is to look for a place where the stream splits. In rare cases, a stream will lose part of its power as it travels downstream and part of the flow goes underground, but don't count on this as a rule. The glacial streams have a couple interesting characteristics. First, they're cloudy, so it's not possible to see the bottom of the stream you're crossing. You just have to guess as to the depth of the stream and the type of rocks/sand in the stream bed. After you've seen a few of these, you can't usually get a pretty good idea of the stream by just looking at the surface. Second, these tend to run higher as it gets sunny and warm. So, your worst crossing may be late in the summer, after a prolonged "heat wave" (or, considering this is Iceland, a "warm wave"). We had no real problems in late June. Temps were cool, and the worst stream we had was only knee deep. A couple strategies to try include waiting for morning when temps are cooler & the flow is reduced, heading up over the ice to avoid stream crossings, or taking a detour to find a known bridge or a dam (such as the bridge 9km northwest of Gćsavötn, or the dam holding lake Hágöngulón).
Tent
We brought a Sierra Designs Clip Flashlight tent on this trip. It's a somewhat light-weight 2-person, 3-season tent. This tent was just barely marginal for a trip like this. If the weather had gotten much worse (and it wasn't too bad for us all things considered), we would have been screwed. A 4-season tent (or at least a 3-season, free-standing tent) with a lot of tie-downs would have been very nice to have. It can get extremely windy out there, and with no trees, and rolling landscapes, finding a sheltered spot can be difficult. Often, the leeward side of cliffs are the same places that blowing sand accumulates, so they're often filled-in and/or sloped. A good 4 season tent would allow you more options to find camp.
There is no way I'd bring a tarp for a long trip in Iceland. It would be pointless, ineffective, and possibly dangerous. There are no trees, and lots of wind and blowing sand. Even in our tent we woke up a couple times covered in dust that had blown in. Dave & I are both pretty experienced long-distance hikers, and we had a good laugh imagining some ultra-light fanatic trying to use a tarp in the Iceland highlands. The only exception might be for the Landmannalauger-Skógar area. You have to camp at the hut sites, and most of them have sheltered grassy areas to pitch your tent. A tarp just might work there if you have poles to use with it & are a little bit lucky with the weather. A bivy bag might work if you can stand the tight space, and also have some plastic bags to store your stuff outside, but it wouldn't be much fun.
Clothing and Gear Notes
Although the temperatures in Iceland in the summer are generally moderate (usually around 40-50F in the highlands, getting up to the 60-70F range on a nice day in the low lands), the "wind chill" can be a major factor. I found that I was hiking with as much clothing as I do in winter back home, where temps are in the 20-30F range. It did cool down at night, but not severely. When you're in a tent, the wind chill no longer applies, and it's not so bad. However, bad weather can blow-in at any time of year, and bring snow and freezing temps. We did have one night of frost, along a lakeshore in the south. But it mostly stayed above freezing.
One thing you should consider is a "real" pack cover. I usually use a black plastic bag, but I'm not sure if that would have cut it out there. At the least, it'd have been incredibly noisy. I brought a sil-nylon pack cover. Make sure your cover can be cinched-up, or ideally fully strapped around your pack so it doesn't blow-off in the wind.
One other thing I wish I brought were ankle gaiters. There is an incredible amount of grit out there, and it gets in everything. Gaiters would have saved me a lot of headaches (er, footaches).
Weather
Generally, temps were in the 40s and 50s, though the wind made it seem much colder. We did get some sleet and snow in the highlands (though it didn't accumulate much). Rain can come with winds, so sideways rain is a possibility (we had about a solid day's worth of that). The weather each morning had virtually no bearing on what the weather that afternoon would be. The only exception was that on two occasions I remember seeing thin, high cirrus clouds as a harbinger of bad weather in about 10-12 hours. But, I didn't see any prior to our worst weather. In general, the wind did seem to die-down in the night, and was worst in the mid-afternoon. Although it's light virtually all the time in the high summer, there is a definite day/night pattern to the weather.
Bugs
There are no mosquitoes in Iceland. I don't know why - maybe the wind? the cold? In any case, count your blessings!However, there are midge flies. These are particularly bad in the north. We had them to some degree from our second day until 2 days south of Mývatn. The midges rarely bite, but when they swarm they are absolutely intolerable. Imagine hundreds of large gnats trying to fly in your ears, nose, eyes and mouth. The only thing you can do is put on a headnet. This works really well, and puts an immediate end to the problem (though eating can be difficult... plus the midges get in your food - ick).
Food
We brought hiking food from home, and mailed a box to Reyjahliđ, and put a box on the bus to Landmannalauger. This worked really well, though it would have been perfectly possibly to buy food at both locations. Buy-as-you-go would be a bit more expensive... and selection is more limited - like a small grocery at Reyjahliđ, and a well-stocked camp store at Landmannalauger. Be sure to ask for some items at Landmannalauger - for example, they have cheese in the back. If you're in a large town, buy food at the "Bonus" (that's a chain) food store, and you'll pay prices comparable to what you'd pay in a mid-range grocery back home.
Stove Fuel
We both used home-made beer-can alcohol stoves. The fuel we used was something called Rod Spirit, available at gas stations by the name T-Röd (it's pink). This isn't exactly denatured alcohol, but worked fine... though it was really sooty. Gas canisters are available just about everywhere, though I'm not familiar with the various types. A lot of tourists camp in the summer, and virtually every town has a campground. So, you'll find regular camping supplies at most stores even in smaller towns.
Direction
We hiked North to South, and I liked going that direction. Although the prevailing wind was in our face most of the way, it put the best scenery last. Also there was something nice about hiking into the wind... like we could see the weather coming or something. Also, when there's just enough breeze to push the midges off your face, but not enough to make them go away completely, you'll be happy to walk into the wind!
Logistics
There is a lot of info about bus routes on the internet, so I won't go into that here. Basically, you can pick up a bus at any stop, and pay the driver or "bus boy" for where you need to go. There are no reservations. Hitching can be done, and is done, but on some roads, there is little traffic, so this can be difficult. Also, many tourists have small, crammed cars, so they may honestly not have room for you and your wet gear. Post Offices are identified with maroon and yellow colors and called Posturinn or something like that.
Internet Resources
Dieter's web site is great, though it's all in German, you can write him with questions. He's been all over the backcountry of Iceland. There are a lot of photos on the site as well.
The Iceland Search and Rescue web site is here.
Andrew Skurka hiked across Iceland on a different route in 2008. His website is a great resource for all kinds of information.Click here.