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Cold conditions
Mid to heavyweight 100% merino wool base layers for thermal warmth without the bulk.
Mild conditions
Lightweight 100% merino wool base layers for active adventures in moderate to cool conditions.
Warm conditions
Lightweight base layers designed for year-round outdoor adventures and everyday training.
200 Oasis+ Suit
Introducing the 200 Oasis+ Suit: the all-in-one base layer tested by elite explorers.
200 Oasis+ Suit
Introducing the 200 Oasis+ Suit: the all-in-one base layer tested by elite explorers.
Base layers for every condition.
Lightweight layers (like 75–175 GSM) are ideal for high-output activity or warmer conditions. Midweight options (around 200 GSM) balance warmth and breathability for everyday layering. Heavyweight base layers (260 GSM and above) offer maximum insulation for cold-weather pursuits.
Cold conditions
Our warmest base layers for the coldest days, made with 100% merino wool. Best for hiking and snow sports.
300 MerinoFine™ Polar
Superfine, ultra-soft 15.5-micron merino wool fibres make the 300 MerinoFine™ our warmest and softest base layer. Specifically designed for comfort in extreme cold, this premium base layer is a winter must-have.
260 ZoneKnit™ Seamless
Experience seamless comfort and performance with our merino blend 260 ZoneKnit™ Seamless base layers. Designed with a second-skin fit, it moves with you effortlessly, featuring body-mapped mesh for breathability and distraction-free movement.
260 ZoneKnit™
Our midweight 260 ZoneKnit™ base layers feature engineered body-mapping technology for warmth and ventilation where you need it most, for targeted performance and body temperature regulation during high-intensity activities in the cold.
260 Tech
When the temperature drops, our 260 Tech base layer offers the thermal comfort you need to keep going in the cold. Made with 100% merino wool, it'll be your go-to piece for winter layering.
260 Tech Vertex
The 260 Tech Vertex is our incredibly warm, women’s-specific base layer. Made with 100% merino wool, it will work hard for you during the coldest months of the year.
260 Tech Vertex
The 260 Tech Vertex is our incredibly warm, women’s-specific base layer. Made with 100% merino wool, it will work hard for you during the coldest months of the year.
Mild conditions
Our midweight base layers offer a little extra warmth when you need it. Best for running, hiking, and snow sports.
200 Oasis
The original merino base layer. Made from our most versatile 100% merino wool jersey fabric, the Oasis is designed for next-to-skin softness while allowing maximum movement. It’s not too heavy and not too light, making it your go-to for year-round layering performance and everyday comfort.
200 ZoneKnit™
Our 200 ZoneKnit™ base layers feature engineered body-mapping technology for targeted performance and body temperature regulation during high-intensity outdoor activities.
200 MerinoFine™ Ace
Our midweight MerinoFine™ Ace performance base layers feature 17.5-micron ultrafine merino wool fibres for versatile comfort in low to medium intensity pursuits.
Warm conditions
Our lightest base layers, designed for year-round, all-season adventures. Best for running, hiking, and snow sports.
175 Everyday
The 175 Everyday base layer is as versatile as it is comfortable. Made with 100% merino wool, it helps keep you warm when it’s cold and cool when it’s warm.
75 Cool-Lite™ Featherlight™
Defy gravity with every stride in the effortless, second-skin comfort of Featherlight™. It’s more than a base layer—it’s lightweight, breathable, and designed to feel like it’s barely there.
Thermal Base Layer FAQs
What is a base layer?
Base layers sit next to your skin, keeping you warm, dry, and comfortable as conditions and activity levels change. The best base layers do more than insulate. They wick moisture and regulate temperature to help you perform at your best. Icebreaker merino wool delivers lightweight warmth, natural odor resistance, and next-to-skin softness. Since 1995, we've crafted merino layers built for comfort, performance, and versatility whether you're hiking, running, or layering up for winter.
What is the difference between thermals and base layers?
Thermals are typically warm, insulating layers for cold conditions, and base layers are designed to sit next to your skin and regulate temperature year-round. Icebreaker base layers use merino wool for natural breathability and comfort in all seasons. Heavyweight merino base layers provide thermal-level warmth—ideal for cold weather, with added natural performance.
Do you wear underwear under a base layer?
You don’t have to wear underwear under a base layer. Icebreaker base layers are made with soft, itch-free merino wool that feels great against your skin, so wearing them directly on your body is completely comfortable. If you do choose to wear underwear, we recommend merino wool underwear to maintain the same breathability, odor resistance, and natural comfort throughout.
Is polyester a good base layer?
Polyester is a synthetic fiber made from petrochemicals and doesn’t make for a good base layer. It traps heat and moisture, which can leave you feeling clammy and uncomfortable. At icebreaker, we choose merino wool—a natural alternative that is breathable, odor-resistant, and temperature-regulating without relying on plastics. It’s better for performance and better for the planet.
