DownUnder Merino Bottom


Regular Price: $89.95

Special Price: $34.97

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    Regular Price: $89.95

    Special Price: $34.97

DownUnder Merino Bottom - Charcoal - back

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  • DownUnder Merino Bottom - Charcoal - back
  • DownUnder Merino Bottom - Charcoal - back


Traditional long johns have spent serious time buried inside clammy waders, leading to some infamous smells you’d rather not remember. Breathe easy. Simms’ DownUnder™ Bottoms are natural born odor killers—thanks to 100% Merino Wool construction—that are soft against your skin and manage moisture better than standard synthetics.


  • All natural 19.5 micron, 220gm unbleached Merino wool for the best warmth and moisture management
  • Flat seam construction
  • Interlock stitch provides great natural stretch and recovery with unprecedented warmth
  • Natural fiber is odor resistant and sustainable
  • Machine wash on gentle cycle, lay flat to dry
  • 100% Merino Wool
  • Approximate weight: 10 oz


Size Chart

Men's Layering Bottom Size Chart

Men's SizesWaist*Inseam**
S 28" - 30" 30"
M 32" - 34" 31"
L 36" - 38" 32"
XL 40" - 42" 33"
XXL 44" - 46" 33"

* This is a body measurement

** This is a garment measurement - inseam measured from crotch to ankle


Layering Philosophy

Product Care

Merino Wool Product Care

Machine-wash cold, tumble dry low. Fabric softeners not recommended.

Flipping items inside out when washing can prolong the look and feel of the fabric.



  • Merino wool is exceptional for performance outdoor wear because the fabric is excellent at regulating body temperature by keeping you warm on cold days and cooler on warm days. It has an excellent warmth-to-weight ratio compared to other wools, in part because the smaller fibers trap body heat. It draws moisture (sweat) away from the skin to provide excellent moisture management, the wool fiber absorbs and releases 10X the moisture of synthetic fibers. The extrafine fibers of Merino wool offer comfortable, no shrink next-to-skin layering without itch or odor.


Customer Reviews

5 Review(s)

5 Item(s)

Awesome base layer. Review by ZR1GOFAST
I live in Alaska and have put these to the test. I own (and now they are collecting dust) North Face, Under Armour and Sitka gear. 2 years ago I bought my first Simms product ( a pair of Windstopper gloves). $6000.00 later I have just about finished switching everything over to Simms products. These Merino Bottom's are simply the best base layer I have used. Warm, comfortable, quick drying, the list goes on. A little pricey but the quality is there. Just like everything life, quality costs....

(Posted on 10/12/14)

Great product. Lightweight. I wear these for a minimum of 14hrs per day during the winter months and frequently work indoors and outdoors. Keep you warm outside and not overheated while working indoors. They also don't stretch out after several hours of use.

(Posted on 1/20/14)

2/713 Review by wierdnjfly
just as awesome as the top

(Posted on 2/8/13)

the only base layer you need Review by Jonathan Heames
these are the only base layer you need, very comfortable in a broad range of temperatures. Think of a down comforter as a bedspread vs. a synthetic one as a comparison. Merino wool has a range of comfort which is unmatched by any synthetics. These are advertised as odor-resistant, I would almost say odor-proof, I'm still trying to find something not pleasant about them after extensive use. Do yourself a favor and use this layer.

(Posted on 11/8/12)

Best next-to-skin layer out there! Review by Yukon_fly
I've logged over 20 frigid days testing my new Downunder Merino bottoms in the ice-cold late winter creeks of south-east Alaska and I can vouch that this is the best next-to-skin layer I've ever fished in. The fit is perfect, they are warm, they dry out quick when wet and they wear really well even after multiple days (they don't start to stretch out at all). I fish Yukon and Alaska well into late fall and early spring and hands down these bottoms are better than any others out on the market - patagonia, sierra designs, arc'teryx, under armour (I should know, as I've worn and worn out most of them). I challenge anyone to find a better product. My only regret is that I don't have the option of rating these a 6 out of 5. Great job Simms!

(Posted on 7/17/12)

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