When running for long distances there are many factors that can make the difference between a relatively comfortable experience, and an agonizing slog with the end nowhere in sight. Amongst the most obvious of these is the state of your feet, and for many people blisters can quickly put an end to what was once a fun experience. Blisters are typically due to a combination of excessive friction and a build up of moisture - two things that are only going to get worse if you are running a 100 miler. On my first 100 mile race last year, I got a hotspot on my forefoot within the first 10 miles and did nothing about it. Running over 90 miles on a gradually worsening blister is not much fun, and by the time I had finished it looked (and felt) pretty bad! However, with the correct choice of footwear it is possible to alleviate the causes of blisters and ensure that you have no excuses but to push on to the finish line!
As the main point of contact with your feet, choosing the right kind of socks can make a huge difference to your comfort while running. A cheap pair of Asda cotton socks might be fine for a quick jog around the block, but they probably won't last you long on the fells. There are several main types available to you, and as usual a lot of it will come down to what works best for you personally. I would love to give the foot-glove socks like Injinji and Wigwam a go (which have individual compartments for each of your little toesie woesies), but I am unfortunately a genetic freak with slightly webbed toes. I am hoping like hell that my daughter is born with Jen's perfect feet instead of my misshapen hooves! My good friend Dan Park has written a great comparison of the two from the point of view of a runner with normal feet here.
Until fairly recently, my sock of choice was the 1000 Mile Fusion sock, a twin layer sock designed in such a way that friction is reduced by allowing the dual layers of the sock to rub against one another. These have worked well for me over the years, but my main issue with them is that they are quite bulky, soak up moisture over long distances, and it is very easy for them to become rucked up inside your shoe which can lead to exactly the problems they purport to solve. These problems are particularly exacerbated on hilly terrain, as I discovered this year at the Lakeland 100.
As I have started to run more, I have found that I prefer to run as unencumbered as possible. With this in mind, I briefly entertained the idea of foregoing socks entirely by running in shoes such as the New Balance Minimus Trail 110s or the Salomon S-Lab Sense (drool...), which are designed with an inner liner to make them comfortable to wear sockless. However, I found that this led to rubbing on my little toe in the MT110s, so decided to look for a relatively minimal sock.
I have heard great things over the years about Drymax socks, but they were only available in the US and seemed to be quite difficult to get hold of. However, when Keith from the Ultramarathon Running Store announced that he was going to begin to stock them, I figured it would be a great time to try something new. Of the vast choice on offer, I decided in the end to go for the Drymax Lite Trail sock, firstly to go with my more minimal sensibilities, but also because I'm a stingy bugger!