Classic Thermal Merino Base Layer Bottom Women's

Uncompromising Warmth for Freezing Canadian Winters

Cold legs can cut a perfect winter day short in an instant. Whether you’re catching first tracks on a freezing morning in the **Wentworth Valley**, snowshoeing through a quiet, snow-covered **Kejimkujik National Park**, or layering up for a damp, windy winter walk along the Atlantic coast, the Smartwool Women’s Classic Thermal Merino Base Layer Bottom is your ultimate defense against the elements. Formerly known as the legendary Merino 250, this heavyweight thermal pant delivers maximum, reliable insulation without ever feeling bulky or restrictive under your gear.

Crafted from 100% premium, ZQ-certified Merino wool using a dense interlock knit, this base layer sits incredibly soft next to your skin while working hard to regulate your body temperature. The natural properties of Merino wool mean it breathes exceptionally well, pulls moisture away from your body during high-output activities, and remains completely odor-resistant over multi-day trips. Designed with a slim, contoured fit that layers beautifully under shells or snow pants, it features a comfortable mid-rise waist with a Merino-lined elastic band and smooth flatlock seams to ensure a completely chafe-free experience all day long.

Key Features

• 100% Premium Merino Wool: Pure, responsibly sourced Merino next to your skin delivers high-tier warmth, breathability, and natural odor control.
• Heavyweight 250 g/m² Insulation: Smartwool’s warmest pure-wool fabric construction, optimized for elite performance in sub-zero winter climates.
• Interlock Knit Construction: Enhances overall garment durability and stretch recovery while providing a super-soft, plush feel against the skin.
• Contoured Slim Fit: Follows the body's natural contours to create an efficient thermal boundary layer that fits perfectly under outer shells without bunching.
• Merino-Lined Mid-Rise Waistband: Features a wide, comfortable elastic waistband lined entirely with Merino wool to eliminate pressure points and moisture buildup.
• Chafe-Free Flatlock Seams: Flat-stitched seams completely remove friction and irritation, making it comfortable for all-day continuous movement.

Best For

• The Effort: Downhill skiing, snowboarding, winter trail running, snowshoeing, and cold-weather backcountry camping.
• The Goal: Eliminating the bite of deep winter freezes and managing sweat during stop-and-go mountain activities.
• The Conditions: Sub-zero environments and damp, freezing winter climates where reliable core insulation is non-negotiable.

Technical Specifications

• Material Composition: 100% Merino Wool (Exclusive of decoration)
• Fabric Weight: 250 g/m² (Heavyweight Thermal)
• Inseam (Size M): 30.5 in. / 77.5 cm
• Rise & Fit: Mid-Rise / Slim Fit
• Style Code: SW019242
• Care Instructions: Machine wash warm gentle cycle inside out, tumble dry low (do not iron decorations, bleach, or dry clean)