Marmot Hydrogen Down Sleeping Bag

-5°C Comfort Limit (EN13537:2012), 310g of 800+ Fill Power Down (US Method)
Weighs 708g (Regular bag)
Code: SS16568V
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The Marmot Hydrogen is one of our bestselling sleeping bags and with good reason. It's the combination of light weight, small pack size, excellent construction and reasonable cost make it a great value choice for 3 season backpacking. The Hydrogen is mummy style sleeping bag featuring 800+ fill power hydrophobic down, a full length zipper, lots of loft and an extremely effective hood design.

Marmot says:

We didn’t think it was possible either, but the Hydrogen is even lighter and more packable than before. The new curved baffles on this bag reduce shifting of the down, allowing this bag to provide enough warmth for cool-weather climbs and backcountry excursions; a new easy-access, fold-down second zipper allows easy ventilation. At just a pound and a half, this bag puts the ultra in ultralight.

Part of Marmot's ultralight range of sleeping bags, the Hydrogen offers a superb balance of quality, low weight, packability, and performance versus cost. It's comparable to many more expensive products, as it is lighter and more compressible than almost all of its competitors.

The Marmot Hydrogen uses 800+ fill power down protected with Marmot's Down Defender to help the down to stay dry longer, loft better when damp and dry more quickly than untreated down. The Pertex Microlight fabric offers a combination of lightweight and good durability plus it's DWR coating will offer some water resistance. The fabric feels really soft which allows the down to loft freely and the slightly brushed feel of the Microlight lining fabric is extremely comfortable against your skin.

The temperature comfort limit rating of -5C sounded optimistic for the amount of down in the bag but having used a Hydrogen in Scotland in March it seems to be correct (using an insulated Thermarest All Seasons SV mat and wearing lightweight baselayers in the bag - the comfort rating is tested using an insulated mat, baselayers and also a hat). On a frosty night I ended up opening the zip slightly as I was so toasty. If you are a cold sleeper this might not stand true but for me it was perfect on a night with temperatures dipping just below zero. This was helped by the excellent hood design which works brilliantly.

Another feature worthy of a mention is the small extra zip which allows you to roll the top of the bag down. This is perfect for a warmer night to avoid overheating or for a cold evening where you want to be sitting in the bag inside the tent.

To steal the words of Mr Remington, having tested the Hydrogen I liked it so much I bought for one myself as I didn't want to give it back. The Marmot Hydrogen is a excellent 3 season bag made even sweeter by the price.

- Reviewed by Ultralight Outdoor Gear

Read reviews here:


Help and advice: Choosing a sleeping bag advice
  EN 13537 rating for sleeping bags explained
  Sleeping bag shape and sizes advice
  Sleeping Bag features Page 1
  Sleepin bag features page 2
  All about down filling in sleeping bags
  • Fold-Down Second Zipper Provides added Ventilation, Easy Access. Anti-Snag Slider reduces Snagging
  • Anatomically Designed Footbox with Wrap-Around Construction increases Warmth
  • Smooth-Curved Baffles Reduce Down Shifting. Nautilus Multi-Baffle Hood limits heat loss
  • Filled and Finished in Rohnert Park, California
  • Certified 800+ Fill Power Goose Down
  • Ultralight Pertex Microlight 20d 100% Nylon Ripstop DWR 1.03 oz/sqyd
  • EN Tested
  • Full Length Locking YKK Two Way Zipper with Zip-Guard Slider
  • Down Defender to Improve Water-Resistance in Wet Conditions
  • Internal Stash Pocket
  • Snagless Insulated Draft Tube
  • Two Way Zipper Sliders
  • Hood Draw Cord
  • Zipper Garage
  • Two Hang Loops
  • Stuff and Storage Sack Included
Regular Long
  • Weight: 708g (excludes storage bags)
  • Fill weight: 310g
  • Fit range: 6"/183cm
  • Interior length: 206cm
  • Shoulder: 155cm
  • Hip: 142cm
  • Foot: 113cm
  • Stuff sack: 15.24 x 30.48cm
  • Stuff sack volume: 5.6L
  • Weight: 790g (excludes storage bags)
  • Fill weight: 380g
  • Fit range: 6.6"/198cm
  • Interior length: 221cm
  • Shoulder: 160cm
  • Hip: 147cm
  • Foot: 117cm
  • Stuff sack: 15.24 x 30.48cm
  • Stuff sack volume: 5.6L

EN Rating

  • Comfort limit: 33.6°F / 0.9°C
  • Lower comfort limit: 23.4°F / -4.8°C
  • Extreme limit: -7.4°F / -21.9°C


  • Shell: Pertex Quantum 20d 100% Nylon R/S 1.03oz/yd
  • Lining: 30d 100% Nylon  DWR 1.09 oz/sqyd
  • Insulation: 800FP Goose Down, PFC-Free Down Defender
Showing our 2 Marmot Hydrogen Down Sleeping Bag reviews with an average rating of Excellent. Would you like to write a review?
Review Summary - 5 out of 5 based on 2 ratings.
May 5, 2020 | Alan
My Favourite bag

This bag is so warm and comfortable and has space to move. The hood and zip flexibility allow you to adjust to suit the ambient temperature. I can fit my Aeros pillow inside the hood and still zip it right up. I have owned a few different bags that have similar specs but found them not as warm and the zip snags or they are just too tight so the down doesn't loft. This is slightly heavier than some but a great bag and worth a few extra grams for a good sleep.

Ultralight Outdoor Gear Limited
March 15, 2020 | Simon Conrad
An excellent bag

There are other bags with similar EN temperature ratings and weight but they are around £100 more expensive, so the Marmot Hydrogen is very good value. The hood is great - so cosy, and the hydrophobic down seems to help in damp weather. The best bit? Well, I'm 189cm tall and need a long bag. Marmot put extra fill into their longer bags which means their long bags have the same EN temperature rating as their standard bags. Check out bags from other manufacturers and you'll see the same fill weight for their long and standards bags. The result? Long bags often have a comfort rating 2-3 degrees less than their standards bags. Well done Marmot for realising that tall people like to stay warm too!!

Ultralight Outdoor Gear Limited