Lithium 20L Daypack
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Light, durable Lithium 20L keeps essentials organized and protected for all-day hikes
What Our Gearhead® Experts Are Saying:
"The Lithium 20L hits that perfect sweet spot for day hikes—big enough for layers, snacks, and water but compact enough that it never feels bulky. The fold-out hip-belt phone pocket is one of those small touches that makes a huge difference on the trail, and the included rain cover means I’m never worried about sudden weather rolling in."
From summit pushes to casual trail loops, the Mammut Lithium 20L Daypack delivers the thoughtful design and comfort we need for full days outside. Its streamlined 20-liter capacity keeps gear organized without overpacking, while the 3D EVA foam back panel promotes airflow to minimize sweaty hotspots on steep climbs. When the weather turns, the detachable rain cover—treated with a PFC-free DWR—keeps our layers and food dry without adding unnecessary weight.
Mammut designed the Lithium series for versatility, and this smaller model proves it. Dual compression straps secure loads of any size, the trekking pole attachment keeps gear accessible, and a fold-out hip-belt phone pocket lets us capture the view without breaking stride. Whether it’s an alpine trail, a quick after-work hike, or a travel companion abroad, the Lithium 20L adapts to every adventure with the precision Mammut is known for.
Details
- Daypack designed for rain-or-shine hiking
- 20L capacity appropriately sized for full days on the trail
- Air channels in 3D foam offer extra ventilation
- Detachable rain cover treated with PFC-free DWR
- Carry system for trekking poles
- Fold-out phone pocket on hip belt
- Compression straps secure the load no matter how much is packed
- Item #MAMU5G9
- Material
- 100% nylon, PFC-free DWR coating
- Volume
- 20L (1220cu in)
- Support/Suspension
- Contact (3D EVA foam)
- Shoulder Straps
- padded, adjustable
- Waist Belt
- detachable, padded
- Hydration Compatible
- yes
- Access
- zippered front panel
- Pockets
- 1 zippered key, 1 zippered front, 2 mesh side
- Trekking Pole Carry
- yes
- Compression
- yes
- Rain Cover
- yes
- Dimensions
- 8.6 x 20.8 x 9.4in
- Claimed Weight
- 1lb 10oz
- Activity
- hiking
- Manufacturer Warranty
- 2 years
Reviews
Q&A
What do you think about this product?
Overall Rating
5 based on 13 ratings
Review Summary
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Selecting an option will reload the available reviews on the pageOctober 16, 2025
Perfect day pack
I’m still breaking it in but it was the perfect size for a fast summit of a 13er in late October. Just enough space for the ten essentials, some water and extra layers. Not too big to be clunky while scrambling on rock. The straps were a little odd fitting but I’m sure if I play with them it’ll be a good fit. Highly recommend for anyone from novice to alpinist who are looking for a smaller daypack!

Originally reviewed on ExpertVoice.com
September 22, 2025
Well thought out Bag
This bag has all the key features that make a great hiking/outdoors pack. Easy hydration setup, well placed pockets and a good amount of storage. The cell phone and key pouch is a great thoughtful detail that helps elevate this pack over the crowd and exemplifies the thinking that went into it. It has been our hiking day pack of choice for traveling light-ish.

Originally reviewed on ExpertVoice.com
August 22, 2024
Day hike warrior
This has been my day hike upgrade all season. Right volume, holds trekking poles perfectly, good belt design and breathable back. Nice outer pocket on the back accessible by sliding one shoulder strap off and pivoting the back in front of you. Decent water resistance. The pearly fabric is a cool touch. I'm very narrow-waisted and the belt straps design makes it hard to cinch down tight enough. The hydration solution is good although the hose exit on one side only reduces options for use. Overall very happy with it!

Originally reviewed on ExpertVoice.com
August 12, 2024
Awesome day pack
The bag has many different straps to adjust the fit for the user. I love the cel phone/wallet bag on the waist. That little touch makes it easier when using all trails app in the woods. Smart touch!

Originally reviewed on ExpertVoice.com
December 12, 2023
Great bag. Taken to South Africa, Mexico and is wonderful. Durable
I actually need another! Great bag can't say enough.

Originally reviewed on ExpertVoice.com
November 22, 2023
Quality pack.
Exactly as advertised. Doesn't have too much going on, and it's great for a short day trip.

Originally reviewed on ExpertVoice.com
November 8, 2023
Best Day Hiking Pack I've owned
Love the fit. It's a little longer than most small day hiking packs, so the hip belt fits and functions like it's supposed to. I don't get the back sweat like other packs I've owned. I'm rough on packs, fighting through trees and shrubs and this pack has held up way better than any other I've used. Very durable shell. Straps and clips are heavy duty for this type of pack. I'm going to buy a few more just to have back ups.

Originally reviewed on ExpertVoice.com
October 31, 2023
Great day pack
- Familiarity:
- I've used it several times
- Size Bought:
- OS
- Height:
- 5' 7"
- Weight:
- 145
Brought this to Japan for a 4 day hike and it was perfect. Love the flexibility of being able to take off the waist belt (I put it in my suitcase to check and used the pack as my in-flight bag). Nice and light-weight. It's a "men's" pack but I am a female and it fits fine although the waist strap is the smallest it will adjust. Great pack in every way. Even has a whistle
July 24, 2023
Very functional
Perfect for a day out. The pack is compact with enough pockets to organize small things but not so many that things get lost in it. The handle on top is steady and the straps are comfortable. My six year old used it on some hikes and it was the perfect size as far as capacity. The fit was a little large but it was made for adults so no surprise. My wife used it as a day pack at an amusement park and a day out with our son. She is not an outdoors person but loved this pack. Thought it was the perfect size. It fit a rain jacket, food, water, and a few odds and ends. I would defiantly recommend this.

Originally reviewed on ExpertVoice.com
July 21, 2023
Everyday adventure pack
Plenty of room, very comfortable for short or long adventures with it! Decent organizational pockets inside and has a spot for a water bladder as well. Nice air flow when worn to prolong the inevitable sweaty back but it cools down nicely when there's a breeze. I'd recommend it for everything short of having to bring a laptop anywhere.

Originally reviewed on ExpertVoice.com
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