| Base layer | Wicks moisture |
| Mid layer | Insulates |
| Shell | Blocks wind & rain |
| Benefit | Adapt to weather & exertion |
Layering is the system of wearing multiple clothing layers — a wicking base layer, an insulating mid layer, and a protective shell — that you add or remove to regulate temperature and moisture outdoors. Layering lets you adapt to changing weather and exertion, and is the foundational principle of dressing for the backcountry.
The three layers
A base layer wicks, a mid layer insulates, and a shell (often a hardshell) blocks the elements.
Why it works
Adjusting thin layers regulates warmth and moisture far better than one thick coat.
Frequently asked questions
What is the layering system?
The layering system is wearing several complementary clothing layers — a base layer to wick sweat, a mid layer to insulate, and a shell to block wind and rain — and adding or removing them to control your temperature and stay dry as conditions and your activity level change.
What are the three layers?
The base layer (next to skin, wicks moisture), the mid layer (insulation, traps warmth), and the shell (outer layer, blocks wind and rain). In cold conditions you might wear several insulating mid layers, and you swap or shed layers as needed.
Why layer instead of one warm coat?
Because conditions and your exertion change constantly outdoors. Multiple thin layers let you fine-tune warmth and dump heat and moisture when working hard, then add insulation when you stop — far more adaptable, and drier, than a single thick coat you can't regulate.
Sources
- Layering basics — The Mountaineers