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NEMO Sonic 0

rated 4.0 of 5 stars
photo: NEMO Sonic 0 3-season down sleeping bag

Used this bag for a February through April section hike of the Applachain Trail this year. It is an outstanding cold weather bag, and as the nights warmed I opened the" gills" to make the bag cooler. Used a large Sea to Summit compression dry sack to carry it.


  • Very warm for the weight
  • You can regulate the warmth using the gills
  • Durable


  • Zipper occasionally hangs, have to zip with caution
  • Expensive

My husband and I planned on hiking the AT this year with a February start. Knowing we would encounter below freezing temperatures for more than a month I searched for a good cold weather bag for the weight ratio.

We settled on the Sonic Nemo, weighing in at about 3 lbs, which when you consider it's rated to zero is pretty light. As noted we used a compression dry sack to compress the bag down – it fits well into the Large size Sea to Summit compression dry sack.  

The bag held up very well to the trail. One morning when we were using a single wall tent there was even frost on the bag. The outer cover did keep the down from getting wet and no harm was done although we did change tents later for a double wall.

I didn't get cold at all on the nearly 500 miles we walked. It did well in the snow and in very cold windy conditions. The coldest night was in the Smokies with temps below freezing and a howling wind but I was toasty in this bag. As the weather got warmer in April I unzipped the two "gills" that are on the bag to vent it and it does make it a cooler. This bag however would not be for temps above 40 degrees, it is just too warm.  

The only improvement that could be made is the zipper. It would occasionally hang, although it was easy enough to get unsnagged. 

The other downside is the bag is pricey. We watched and when Nemo put them on sale we purchased two of them.

Overall the Sonic Nemo is a decent value for the money. 

Source: bought it new

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Price Current Retail: $366.30-$649.95
Historic Range: $287.97-$699.95
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