Ski underwear needs to be warm and comfortable, but more importantly, it needs to fit well and it needs to be moisture-wicking. These features can affect the overall price of the underwear set, so you will need to decide how much money you are comfortable spending on the underwear before you go shopping. Researching popular brands and reading customer reviews on the Internet is a good way to become familiar with the pros and cons of each type of underwear. When shopping for ski underwear, look for clothing made from synthetic fibers that are fast-drying and tight-fitting yet comfortable.
Some ski underwear sets are made from thin layers of cotton or wool. Cotton ski underwear should be avoided, as cotton tends to get wet quickly and stay wet for a long period of time, which means the wearer is likely to get cold. Wool is quite warm even when wet, but it can be extremely uncomfortable and itchy. Very often wool is combined with synthetic fibers to improve the comfort and drying capabilities of the garments, though this type of underwear is likely to be fairly expensive.
Synthetic fibers made from polypropylene or even polyester are the best choices for ski underwear offerings. These garments are lightweight, generally tight-fitting and comfortable, and moisture-wicking, which means they will pull moisture from sweat away from the body to keep the skin dry and comfortable throughout the day of skiing. These synthetics also tend to be quick-drying, so they can be worn for long periods of time comfortably. The downside to synthetics is the cost and the odor: these garments tend to collect body odor, and it can be difficult to remove even after repeated washings. This is usually not a problem during athletic activity, but it may be noticeable during downtime and rest periods.
Be sure to choose ski underwear that is durable and comfortable. Some versions of this type of underwear will come with padded or reinforced shins, since this part of the long underwear will be in constant contact with the ski boot. This can lead to discomfort on the legs, but also damage to the underwear or the liner of the boots themselves. Choose underwear with seams that do not interfere with the skin or any part of the boot, whenever possible. If seams are located in these areas, make sure they are low profile seams that will not end up chafing the skin.