Whether hiking, trail running, or skiing, the wrong clothing can ruin your day. You need to avoid overheating or getting chilled, wearing the wrong gear, or overpacking. The three-layer system solves this challenge.
What is the layering system?
The layering system is standard practice across outdoor sports like hiking, mountaineering, trail running, running, and skiing. Like the layers of an onion, it involves stacking multiple functional layers rather than wearing a single bulky jacket, optimising performance through superior temperature regulation.
The layering system offers numerous benefits, first and foremost adaptability and comfort. You can add or shed layers depending on effort levels and weather conditions. Air trapped between layers enhances insulation for optimal thermal efficiency. Sweat is wicked away efficiently to prevent post-effort chill. Plus, versatile gear works across multiple seasons and sports.
Traditionally, the layering system relies on three layers with distinct functions: a breathable base layer, an insulating mid layer, and a protective outer shell. In extreme conditions, you can layer up to 4 or 5 garments.
The base layer
The first layer, or base layer, is breathable. Its primary role is to wick sweat away. During exertion, your body produces moisture; if trapped against the skin, it quickly chills you down. Thanks to the thermal regulation of a technical base layer, skin stays dry and the body retains heat. If you are wondering what clothing to choose for hiking, a breathable base layer is an absolute essential.
The base layer forms the foundation of the layering system, so materials must be chosen carefully. Synthetic fibres (polyester, polyamide, elastane) are an excellent option: they provide high breathability, dry quickly, and are budget-friendly, though they can hold odours. Merino wool delivers outstanding temperature regulation, natural antibacterial properties, softness, and comfort, though it comes at a higher price point and is less durable.
For the best balance of warmth, comfort, moisture wicking, and durability, opt for clothing combining merino wool with synthetic blends. Whatever you do, avoid cotton, which traps moisture.
Multiple garment options exist depending on your activity and weather. In winter, thermal base layers are recommended. For summer or mid-season outings, go with short- or long-sleeved hiking T-shirts. Wear them next to skin without feeling restrictive for maximum wicking efficiency.
The mid layer
The second layer, or mid layer, provides thermal insulation. Its primary role is to trap body heat within the fibres and fabric structure while channelling moisture from the base layer to the outer shell. It is the easiest layer to add or remove on the move.
Just like base layers, the mid layer comes in various technical fabrics. Synthetic fleece is lightweight, warm, breathable, fast-drying, and affordable, though it offers minimal resistance to wind and rain. Synthetic insulated jackets maintain warmth even when damp and dry fast. Goose or duck down jackets deliver exceptional warmth-to-weight ratio and packability, but require care around moisture and carry a higher price tag.
If you are heading out hiking, fleece jackets are a must-have. They perform brilliantly in cool, dry conditions, especially at the bivvy in the evening. For intense cold and dry weather, down jackets—particularly natural down—provide maximum thermal insulation. Finally, softshell jackets deliver the ultimate balance of warmth and weather protection, combining insulation, wind resistance, and breathability for shoulder-season outings.
The outer layer
The third layer, or outer shell, is the protective barrier. In the layering system, it is the layer directly exposed to the elements. It shields against wind, rain, snow, and extreme cold while preserving the performance of the two underlying layers.
Most outer layers are waterproof and breathable. We recommend choosing a technical membrane like Gore-Tex® or Cimalp's Ultrashell® technology, which keeps rain out while venting internal moisture. Some jackets feature durable water repellent (DWR) finishes to shed surface water. Others use windproof fabrics—ultralight and built to block wind chill, though not intended for sustained downpours.
Your choice of outer layer depends primarily on your activity. Hardshell waterproof jackets are essential for long-distance hiking, trekking, or mountaineering, providing a robust protective barrier in all conditions. Windproof jackets are ideal for fast hiking or trail running, offering packable, ultralight protection. Finally, ponchos or rain capes suit occasional outings: they cover you and your pack affordably, but fall short in high winds and offer limited breathability.
The layering system is the most effective way to dress for outdoor activities. By applying the three-layer principle, you will be set for hiking, trail running, or skiing in total comfort. For complete protection, do not forget to shield your extremities from the cold.
