It's important to relate the thickness of your sock to the fit of your footwear. The thickness of your sock can change the volume of your foot and potentially make your footwear feel too tight. In preparation for your activity try your footwear on with the sock you intend to wear.
There are many types of socks for many different activities. Having the right socks for each activity can make you feel more comfortable and therefore push your limits even further.
For example, you wouldn’t wear a running sock whilst out mountaineering because the level of cushioning and warmth would not be adequate enough for what is required. In the same respect you wouldn’t wear a mountaineering sock whilst out running as the warmth and cushioning would far exceed the level needed and make for a very uncomfortable sweaty run.
When choosing socks it is also dependent on the type of footwear you choose. Mountaineering boots are often built to accommodate a warmer sock for insulation and a thick durable outer for protection, whereas running shoes are often built with a sock-like slender fit for precision and sensitivity when out on the trails thus requiring a well-fitting skin-like sock with cushioning only in key areas.
The fabric composition of your socks makes a huge contribution to your comfort. Synthetic fabrics and natural merino wool are great options for socks. They wick moisture away from the foot, dry quickly and provide a degree of insulation whether they are wet or dry. The yarn is also much finer making them softer against the skin.
Cotton socks are a very popular casual choice but they’re not appropriate for strenuous activities such as hill walking, as they will absorb the moisture from your foot and keep it next to your skin for the rest of the day, making a perfect home for foot fungi that can be tricky to get rid of. They’re also coarser than other fabrics often leading to sore spots and blisters where alternative socks would not and they have zero insulation capabilities when they’re wet.
Whether you choose to wear one pair of socks or two is largely a personal preference. When hiking, those who are prone to blisters may choose to wear two pairs; a dedicated liner pair and a thicker cushioning pair. This will help to reduce the friction and lift the moisture from the skin, keeping it drier.
Waterproof socks are ideal for use in non waterproof footwear, when worn in wet conditions. Those such as Sealskinz usually have a Merino wool liner for comfort and warmth and a hydrophilic membrane that’s great at keeping your feet dry and comfortable when worn in wet conditions.
1) Moisture and friction together causes blisters, take away one of these two elements and you will reduce your chances of getting a blister.
2) Good technical socks can be expensive and always perform better when clean, save a little cash when going on a long trip by hand washing them at the end of the day and leave them to dry overnight if the conditions allow.