Merino is a breed of sheep that are prized for having some of the finest and softest wool of any sheep. Merino wool is commonly used in high end performance athletic clothing for running, hiking, skiing, mountaineering, and cycling.
Merino wool has the ability to regulate body temperature keeping the wearer warm without overheating them. It also has a unique natural wicking attribute that helps keep the skin dry during strenuous activity.
Merino wool is slightly water resistant but it can retain water up to 1/3 of its weight. However, unlike cotton, it retains its warmth even when wet helping the wearer avoid hypothermia. Merino wool has a much higher warmth to thickness ratio than other types of wool allowing the athlete to be lighter weight and less bulky.