What Our Gearhead® Experts Are Saying:

“This one piece is the ultimate base layer for skiing, snowboarding, or even hut trips. It’s all the benefits of Smartwool’s 100% Merino wool in a seamless head-to-toe package, with details like a zippered drop seat and flatlock seams that make it super functional.”

Built for the coldest days and longest adventures, the Smartwool Classic Thermal Merino Base Layer One Piece provides full-body coverage in one streamlined design. Made from 100% Merino wool, it naturally regulates temperature, manages sweat, and resists odor, keeping you comfortable from first chair to last run.

A slim fit and interlock knit construction enhance warmth and next-to-skin softness, while thoughtful details like a zippered drop seat, set-in sleeves, and flatlock seams ensure all-day comfort. Whether you’re layering up for deep winter skiing or cozying up in the cabin, this one piece makes cold-weather layering simple and smart.

Similar Women's One-Piece Long Underwear & Baselayers

Women's Long Underwear & Baselayer Tops (88)

Women's Midweight Long Underwear Tops (61)

Women's Lightweight Long Underwear Tops (17)

Women's Heavyweight Long Underwear Tops (10)

Women's Long Underwear & Baselayer Bottoms (60)

Women's Midweight Long Underwear Bottoms (33)

Women's Heavyweight Long Underwear Bottoms (14)

Women's Lightweight Long Underwear Bottoms (13)

Women's One-Piece Long Underwear & Baselayers (57)

Women's Bike Base Layers (26)

Brand

Backcountry (3)

Beyond Yoga (1)

Burton (1)

Carve Designs (6)

Cotopaxi (1)

Dickies (4)

DU/ER (1)

FP Movement (4)

Free Fly (1)

Free People (6)

Helly Hansen (1)

KAVU (4)

Mountain Hardwear (2)

Parmi Lifewear (1)

Patagonia (1)

Picture Organic (2)

prAna (4)

Roark (1)

Rolla's (2)

Sendero Provisions Co. (1)

Smartwool (1)

Stan Ray (1)

Tentree (1)

Toad&Co (2)

Topo Designs (1)

Wildfang (3)

Wondery (1)

Clothing Size

11 (34)

7 (33)

4 (30)

8 (30)

14 (28)

10 (3)

3 (3)

6 (3)

0 (2)

12 (2)

9 (2)

13 (1)

2 (1)

22W (1)

5 (1)

L (1)

M (1)

S (1)

XS (1)

Color

.css-yab3pc{height:23px;width:23px;border-radius:50%;margin-right:var(--chakra-space-1);background-color:#000;box-shadow:inset 0 0 0 3px #fff,0 0 0 1px #ccc;}black (21)

.css-2gcc7g{height:23px;width:23px;border-radius:50%;margin-right:var(--chakra-space-1);background-color:#369;box-shadow:inset 0 0 0 3px #fff,0 0 0 1px #ccc;}blue (15)

.css-1nhbdo3{height:23px;width:23px;border-radius:50%;margin-right:var(--chakra-space-1);background-color:#093;box-shadow:inset 0 0 0 3px #fff,0 0 0 1px #ccc;}green (12)

.css-7bc19j{height:23px;width:23px;border-radius:50%;margin-right:var(--chakra-space-1);background-color:#963;box-shadow:inset 0 0 0 3px #fff,0 0 0 1px #ccc;}brown (10)

.css-2z3tn4{height:23px;width:23px;border-radius:50%;margin-right:var(--chakra-space-1);background-color:#efb780;box-shadow:inset 0 0 0 3px #fff,0 0 0 1px #ccc;}beige (6)

.css-yle8g5{height:23px;width:23px;border-radius:50%;margin-right:var(--chakra-space-1);background-color:#fff;box-shadow:inset 0 0 0 3px #fff,0 0 0 1px #ccc;}white (5)

.css-19q3wht{height:23px;width:23px;border-radius:50%;margin-right:var(--chakra-space-1);background-color:#f39;box-shadow:inset 0 0 0 3px #fff,0 0 0 1px #ccc;}pink (4)

.css-uc0kmc{height:23px;width:23px;border-radius:50%;margin-right:var(--chakra-space-1);background-color:#f93;box-shadow:inset 0 0 0 3px #fff,0 0 0 1px #ccc;}orange (3)

.css-1ryiaxq{height:23px;width:23px;border-radius:50%;margin-right:var(--chakra-space-1);background-color:#ff0;box-shadow:inset 0 0 0 3px #fff,0 0 0 1px #ccc;}yellow (3)

.css-1pgjne4{height:23px;width:23px;border-radius:50%;margin-right:var(--chakra-space-1);background-color:#ccc;box-shadow:inset 0 0 0 3px #fff,0 0 0 1px #ccc;}gray (2)

.css-1ingyn9{height:23px;width:23px;border-radius:50%;margin-right:var(--chakra-space-1);background-color:#639;box-shadow:inset 0 0 0 3px #fff,0 0 0 1px #ccc;}purple (2)

.css-1c4afls{height:23px;width:23px;border-radius:50%;margin-right:var(--chakra-space-1);background-color:#f00;box-shadow:inset 0 0 0 3px #fff,0 0 0 1px #ccc;}red (1)

Sale

10% and more (57)

20% and more (57)

30% and more (55)

40% and more (49)

50% and more (34)

Gender

female (53)

black (21)

blue (15)

green (12)

brown (10)

beige (6)

white (5)

pink (4)

orange (3)

yellow (3)

gray (2)

purple (2)

red (1)