Mountain sports can be physically demanding and whether you’re walking uphill or skiing down, the exertion creates sweat. Base layers are designed to move this sweat away from your skin. This process is called wicking, and it is an essential part of any mountain clothing system. Synthetic base layers use capillary action to draw moisture through to the outer surface allowing evaporative cooling. Merino base layers use fine-grade wool (often sustainably farmed from sheep in New Zealand).

It is especially important for winter thermals to have performance and wicking properties, because sweat can be very uncomfortable when it cools during inactive phases. Therefore avoid cotton at all costs – it will hold sweat next to your skin, feeling clammy while you’re hot and then cooling rapidly when you stop being active. Modern waterproofs and fleeces are highly breathable, but only if sweat is able to reach them.

A fully-functioning base layer provides the foundation for an effective clothing system so take your pick from our extensive range of performance base layers from top brands Icebreaker, Mons Royale, The North Face, Arc’teryx and Skins.