This Editors' Choice winner provides a fantastic balance of warmth and breathability. Its fabrics are the coziest out there. It'll keep you comfortable whether you're curling up next to a fire or crushing it while a storm pounds the area.
Performance Comparison
The Smartwool 250 bottom offers plush comfort for a variety of outdoor activities. Take it running, climbing, hiking and more! The thicker fabrics provide a wide range of thermoregulation that keep you warm and happy this cold season.
Warmth
Offering 250-grams of plush warmth in the form of thick merino wool fabrics, this mid-weight long underwear bottom is plenty warm for cold weather. The fibers are hydrophobic, repelling water and sweat, and ensuring that it wicks away from the skin. The fibers insulate, even when fully saturated, and the thickness of the fabrics provide a cozy experience that is comfortable for all-day wear. This midweight merino wool contender is super warm and a great option for cool to cold weather wear.
In our testing, we sailed the North seas while exploring the Faroe Islands. We wore while checking out glaciers and icebergs in Iceland, and while battling polar conditions in the Colorado mountains. We tested this piece of gear in everything from warm to super cold conditions.
A great base layer is worn underneath a solid pair of hiking or snow pants. Here we test the Smartwool 250 (our Editor's Choice winner) while hiking up to the highest sea cliffs in the world in the remote Faroe Islands. A perfect option for this backpacking escapade!
When worn under a pair of hiking or ski pants, the thicker fabrics do a great job insulating, even if the pant lacks insulation. While in motion, the hydrophobic merino fibers wicked away moisture and didn't hold it in the fabric…even when ventilation wasn't an option. In all cases, our skin felt dry even after moving then sitting for long periods of time. As a result, we deem this a toasty yet breathable base layer bottom that will perform in everything from sub-zero conditions with an appropriate layering system.
The Smartwool 250 offers thicker fabrics that are still breathable but offers better warmth then thinner fabrics.
Comfort and Fit
Comfort and coziness is key to making sure a piece of long underwear is comfortable right against the skin for all-day wear. In this piece, comfort comes in the form of super soft fabrics that are thick and cozy to the touch.
The merino wool is not itchy, even when wet, and wears for days on end. The broad waistband has a layer of soft cushioning. There are no weird points of constriction and the ankles and waistband are quite elastic, fitting around thin and thick appendages nicely.
A look at the flat seams and how the waistband sits against the skin.
The thicker waistband is encapsulated by a thick and plush fabric that feels good against the skin.
The length of the pant is on point. It's not too short nor too long. For a woman who is 5'6", the length comes right down to the ankle and offers even a little extra fabric.
Smartwool 250 Front -- some gussets around the crouch don't make for a good look, but it's ultra comfortable.
Smartwool 250 Midweight - good mid-length.
Back -- model is 5'6" and 140 lbs.
This was our only base layer on our trip to the Faroe Islands and Iceland. On this trip, we wore it for days on end without washing it. In these humid conditions, she felt warm and comfortable, even while sailing on the fiercely windy and cold high seas. While bobbing on a boat for hours, waves typically rushed over the bow, soaking us. In all cases, even when the fabric got wet and cold, it maintained warmth and stayed comfortable.
Cold weather on the North Sea was a perfect place to test comfort...especially when we couldn't wash our clothes (or ourselves) for days on end.
Our only caveat is that when worn actively, even though the fabrics have a stretch that conforms nicely to the body, the material can lose its tautness and stretch out a bit. Under a layer, this isn't a big deal, but we noticed that, like other merino wool contenders, it didn't retain its shape as well as synthetic options. That said, it still was able to do its job for days on end. This is a thick and comfortable base layer that feels nice on the skin. You'll have a hard time taking it off once you've put it on.
A look at the hems around the ankle. Super cozy and elastic.
The 250 weight base layer bottom comes in three different styles. Choose from the full length or three-quarter length pant. If you prefer to be completely encased in lavish merino fabrics, take a look at the awesome onesie that will cover you from head to foot!
Breathability and Drying Speed
Constructed of 100 percent merino wool, this bottom is exceptional when it comes to breathability. First of all, the merino wool fibers are nice and hydrophobic (water-hating). As a result, it wicks away moisture well. When met with a heavy downpour, you might find the material to saturate quickly and hold more water. However, despite this fact, the fabrics breathe very nicely and dry fast. Second, the fibers can move moisture from the skin to the outside of the shirt. Merino wool provides more warmth when wet than other synthetics, and this shirt is no exception. When running or sweating, we found that we didn't get clammy or wet, even when our upper layer didn't vent as well as we wished.
Throughout our testing, we took this piece running, sailing and hiking. We even wore it while climbing and doing random chores around town. In all cases, with both high and low output activities, the fabrics wicked away moisture and breathed exceptionally well. In our at home tests, we noticed a few interesting things. When placing water on the material, it beaded but did not readily absorb.
Water beads and doesn't soak in easily. The hydrophobic fibers do a great job breathing and wicking away moisture...until agitated.
This shows the water repulsion of the merino wool. When putting it in a sink full of water (waiting for it to absorb and sink), the piece just floated for many minutes…and didn't sink. In comparison, all synthetic competitors immediately consumed water and sunk. As a result, the fabric repels water better than other synthetic contenders. This shows its ability to wick water, which attributes to its high breathability and drying speed.
A heavier weight article, but it still feels lightweight when wearing.
When fully dunking the bottoms underwater, we learned that because of thicker fabrics, it absorbed more water than thinner contenders like the Smartwool 150 Merino (10.25 grams). However, when doing the dryer tests, it took a similar time to dry and thus proved to have a faster rate of drying than other tops. Overall, this is quick to dry bottom wicks very well.
Testing out the mobility of the fabrics on this in-place elliptical machine. This pant was perfect to take out in zero degree temperatures in cold-humid weather.
When running and exploring, we learned that while the fabric breaths, the thickness of it doesn't offer the same level of airflow that thinner contenders offer. However, when worn with a layered system, it provides a fantastic level of warmth for the level of breathability it offers. Overall, these bottoms effectively thermoregulate though exceptional breathability and fast drying speed. Wear them on your next adventure where you might be hiking in cold weather or hanging out in frigid conditions.
Durability
Smartwool offers a great performing top that doesn't shrink or change its shape too much use. Our only caveat is that the material can easily tear and wear through. Being constructed of merino wool materials that aren't particularly tightly knit, it is fragile. Designed to be worn underneath another piece of clothing, this is expected. Also to note, construction of the fabric is good, but not perfect. We noted a couple of fly-away threads on the stitching and some minor pilling after washing. As a result, it's not the most durable option out there, but it's also lasted us a few years thus far in its use.
In our testing period, we accidentally snagged the fabric on a sharp edge while preparing for bed underneath the cabin in our sailboat. The material immediately tore, earning its first hole. After this experience where we didn't have it layered underneath another layer (i.e., while milling around the cabin), we received a few more holes from casual encounters with uneven surfaces. While this was sad, the holes didn't continue to rip, nor did they radiate from that spot. Aside from these rips, the material does hold up. The shape, after months of use, is roughly the same, only stretching out in between washes. Also, being merino wool and a natural fiber that repels odor, we didn't find any stink lingering in the fabrics, even after wearing the bottoms for over five days without a shower (ew!). Overall, durability is sufficient but not as good as synthetic competitors like the Arc'teryx Rho LT.
Best Application
With an amazingly wide range of thermoregulation that does well in cool to frigid weather, this midweight base layer bottom has a plethora of uses. During any kind of cold weather its great to layer underneath a solid pair of pants. Even though the fabrics are thicker than its contenders, it can fit nicely underneath a pair of looser hiking pants (you might have a hard time with skinny jeans) or snow pants. Since the organic materials are naturally odor resistant, it wears for several days without washes in between. We'd recommend it for mid to low output activity in cold conditions. If you plan on going to the coldest places on earth, we'd recommend a thicker option.
Backcountry skiing on Baker. The Smartwool base layer proved to be a great partner on these cold days in the humid, wet climates of Washington. Wear this layer anywhere you please!
Value
Retailing for $95 this is the most expensive bottom in this review. Given that it performs so well, we'd say that the price is worth the performance. However, there are other merino options out there that offer a little less insulation for a lower price with similar properties. Take for example, our Notable Mention, the REI Co-op Merino Midweight Bottoms that goes for $15 less.
Smartwool does offer a lifetime guarantee on its products. If you're not happy, give them a call and they'd be happy to help you out.
Conclusion
This Editors' Choice winner is versatile and offers an exceptional level of performance across all metrics! It's our favorite because of its exceptional cozy fabrics that make you want to curl up and cuddle with your puppy while stormy weather blows. If you're the kind of girl that likes to get out in that nasty weather, it'll keep you warm while you take on the elements.
