Marmot Mad River 40 Sleeping Bag: 40 Degree Down

Mad River 40 delivers ultralight warmth, water-resistant down, and packability for summer backpacking

What Our Gearhead® Experts Are Saying:

"The Mad River 40 is my go-to sleeping bag for warm-weather backpacking. It’s lightweight, packs down small, and the 650-fill ExpeDRY down stays lofty even in humid conditions. The dual-zipper design makes it easy to vent on hot nights, and the draft collar helps keep warmth in when temperatures dip. It’s comfortable, breathable, and perfect for summer nights on the trail."

For warm summer nights in the backcountry, the Marmot Mad River 40 Sleeping Bag offers lightweight comfort without unnecessary bulk. Packed with 650-fill-power ExpeDRY down, this bag delivers high-loft warmth while drying quickly in humid or damp conditions. The fully recycled nylon shell and lining reduce environmental impact, making it a sustainable choice for eco-conscious adventurers.

Designed for versatility, the full-length snag-free zipper allows for easy entry and exit, while the short right-side zipper provides extra ventilation on warmer nights. The draft collar adds warmth when the temperature drops, and the anatomically wrapped footbox keeps feet cozy without feeling restrictive. Whether we´re cowboy camping under the stars or setting up in a breezy tent, the Mad River 40 offers the perfect blend of comfort, packability, and sustainability for summer adventures.

Details

• 40°F down sleeping bag built for summer backpacking and warm-weather camping
• 650-fill-power ExpeDRY down provides lightweight warmth and quick-drying performance
• 100% recycled nylon ripstop shell and taffeta lining reduce environmental impact
• Full-length snag-free zipper allows for easy access and ventilation control
• Short right-side zipper offers extra airflow and fold-down comfort
• Draft collar and anatomically wrapped footbox enhance warmth and sleeping comfort
• Includes a compression stuff sack and storage bag for easy packing
• Item #MARZA4T

Tech Specs

Material

100% recycled nylon ripstop

Insulation

down

Shape

mummy

Zipper

full-length

Max User Height

[short] 66in, [regular] 72in, [long] 78in

Shoulder Circumference

[short] 60.6in, [regular] 63in, [long] 64.5in

Venting

full-length zipper

Degree

40°F

Storage Sack

yes

Stuff Sack

yes

Activity

camping, weekend camping

Manufacturer Warranty

limited lifetime