REI Co-op Merino Wool Ultralight Crew Review

The REI Merino Wool Ultralight Crew offers a breathable, lightweight ride suitable for all sorts of adventures, including ones in heat. It dries quickly and offers insulative warmth when wet. It isn't the most padded and doesn't offer the most stand-alone warmth, but it boasts an excellent value for an ultralight sock.

Performance Comparison

Comfort

This hiking sock is a nice fit for those that prefer a less cushioned sock with just enough padding in all the right places. It is made with 72% merino wool, 26% nylon, and 2% lycra textiles. We tested it while trail running, hiking on steep terrain, and backpacking.

This sock is dubbed “ultralight” meaning that it has a thin layer of material throughout, though it also has a little extra thickness on the heel and forefoot. It is suitable for warmer weather, and if your feet tend to sweat a lot, it'll do you good in cold weather as well. The padding is found in all the right places, with an extra layer of heavily looped merino wool at the heel and forefoot.

The materials aren't the softest that we've tested, but given it is made of primarily merino wool, it doesn't scratch or itch. We also appreciate the elasticized toe and calf collar, which didn't slide down or bunch when walking for miles on end. The longer length is suitable for use with a pair of hiking boots and offers nice protection when you come across thorny bushes or taller grasses.

On a longer 10 mile hike where water abounded, the sock retained its shape, even after getting wet. We also appreciate that the toe stayed intact and didn't bunch or roll. Overall, even though it's not the most padded or cushioned like other high performers, it offers a lighter architecture with nice stretch and resiliency, earning it an average score in this category.

Wicking and Breathability

We appreciate the combination of synthetics and merino wool in a lightweight design, making this sock excellent at wicking and breathing. It offers ventilation in all the right places, around the arch, and through the leg. For warmer weather, this is a hiker we reach for, simply because of its extra-breathable design.

When we flip the sock inside out, the first noticeable feature is the big loops in the fabric. For sweaty feet, this is key for wicking sweat. When we ran in hot weather to test the wicking efficiency (in a breathable pair of shoes), it seemed that sweat was easily transported from the skin to the outside of the sock, keeping our feet nice and dry, even in hot weather.

We also tried it out while hiking in the desert in temperatures that rose to around 90 degrees. We don't love hiking in this weather, but we needed to see how it would do. Given its lightweight design, our feet stayed relatively comfortable, staying dry without feeling like they were on fire. While sandals are preferable for these conditions, we are pretty happy with this performance in warmer weather and would choose it where a full-length hiker might be required.

Warmth

The REI Ultralight offers nice insulation when wet, but isn't very warm on its own. We tested it while backcountry skiing and sleeping in colder weather on a camping trip. For an ultralight design, it does provide surprising thermoregulation during cold weather sports while helping to keep your foot dry, which means you do stay warmer. However, as soon we stopped moving or had to stand around in cold weather, our feet felt cold.

When backcountry splitboarding, we tested it to see if it would keep our feet dry. We also wanted to know if it would stay warm when wet (or had a little stagnant sweat stuff on them). On the uphills, we did some work, sweating it out on the steeps. Since our snowboarding boots aren't the most breathable, we noticed that some of the water stayed on the sock, but our skin still felt warm and relatively dry. When it was time to transition into snowboard mode, we stopped. The windchill was felt on this particularly cold day. After about ten minutes, our feet started to cool down.

In other tests, we dunked our feet (with the sock on) into the water while on a colder winter hike and continued to hike in the cold winter air. The ultralight design of this sock didn't offer as much insulation as a more heavily padded version, but it still offered a tiny smidge of insulation. On this active winter hike, our feet stayed relatively warm, but when we stopped, they cooled down faster than with a thicker design.

During a sleeping test, we tested in temperatures that hovered around 32 degrees Fahrenheit on a camping trip. During the night, our feet stayed toasty in our zero-degree sleeping bag. When we got up to go to the bathroom, we threw on a pair of sandals. Here, we noticed the air whipping right through the sock, not offering a lot of insulative warmth on its own.

Overall, we deem this sock to provide just the amount of warmth you'd expect from an ultralight hiker. Not a lot on its own in cold weather, but just enough to perform throughout the seasons while you're on the move. If you have sweaty feet, this construction might be a good fit for you, but if you run cold, opt for a little more insulation.

Durability

During our testing period, we put about 60 miles on it (and we continue to do so). After these miles where it got wet and deformed while skiing, running, hiking, and hanging around, it still looks relatively fresh. We've washed it several times and notice just a small amount of pilling in the calf area.

Given the lighter weight, we wouldn't expect it to last as long as a more heavily padded option, and the seams and stitching look to be well crafted, but not as tight as other contenders that have stood the test of time. When we spread our toes, we can actually see our skin through the airy stitching. While we haven't yet seen a hole or pushed the sock to its limit, we think it offers middle-of-the-road durability simply based on the weight and the look of its face stitching and weaving.

Drying Speed

The REI Merino Wool Ultralight Crew offers impeccable drying speed, doing well in our field and at-home tests. It scores high on our charts, and one we'd trust in wet conditions. We tested it while hiking and performing a dryer test at home.

The ultralight design and airy fabric construction are conducive to quick-drying capabilities. It is made of merino wool that initially absorbs quite a bit of water. During our dryer tests, it took only 60 minutes to dry at low heat, meaning it performs in the high ranks in comparison to the rest of the contenders. Out in the field, we ran through muddy puddles in shoes with good drainage. Our feet were dry after 15 minutes of hiking in 70-degree weather where the conditions were dry (not humid). The ultralight construction makes this one of the fastest to dry socks in our testing.

Value

Are you seeking a deal? For its excellent ultralight performance and price, this isn't one to be missed. During our testing period, it showed limited signs of durability even after wearing it through mud, snow, and water for 60+ miles. Plus, it's backed by REI's guarantee, which we've used for other products. If you don't like it, you can return it, no questions asked. We've used the warranty before and have been very happy with REI's customer service and commitment to ensuring that their customers find the right gear for them. Overall, a good deal.

Conclusion

The REI Co-op Merino Wool Ultralight Crew is a high-value lightweight hiking sock that we wholeheartedly recommend. It features a breathable and light design that's suitable for warmer weather and a myriad of uses. While it doesn't boast the most stand-alone warmth or cushioning, it's still one that we include in our regular rotation for its stand-out breathability and speedy drying performance. Its performance comes close to our highest-scoring contenders, yet its price is significantly less. The savings especially grow if you're grabbing multiple pairs.