Mammut Lithium 25 review: a feature-rich Swiss 25L daypack

The Mammut Lithium 25 is a 25-litre hiking daypack from one of the oldest names in the mountains. Mammut has been making alpine kit in Switzerland since 1862, and that pedigree shows up here as a pack that is more thought-through than most at this size. The Lithium 25 is billed as a lightweight, fully-featured multi-talent for day hikes and bigger days out, and that is a fair description: it carries a genuine day's worth of kit, keeps it organised, and comes with an integrated rain cover that most rivals make you buy separately. My one-sentence verdict is that this is one of the best-equipped 25-litre daypacks you can buy, and if you want features and organisation over the lowest possible weight, it is worth the premium price.

Who the Lithium 25 suits

This is a pack for the day hiker who likes their kit organised and does not want to think about the weather. If you do three to seven hour walks across coast paths, downland, forest and the odd hill day, and you want a pack that swallows layers, food, water and waterproofs while keeping the small stuff to hand, the Lithium 25 is built for exactly that. The integrated rain cover and the fold-out phone pocket on the hip belt tell you who Mammut had in mind: someone who wants the details sorted rather than a stripped-back sack.

It also suits anyone who values build quality and is happy to pay for it. Mammut sits at the premium end, and the Lithium is priced to match at around £120. What you get for that is Swiss construction, recycled 100D ripstop fabric and a feature set that punches past most 25-litre packs.

Who should skip it? Gram-counters. At around 851g the Lithium is not an ultralight pack, and if your priority is the lowest number on the scales you will find lighter 25-litre options. Those packs almost always drop the rain cover, the padded hip belt and some of the organisation to get there, so you are trading features for weight. If that trade appeals, look elsewhere. If you would rather carry a slightly heavier pack that does more, read on.

Specs

Capacity

25 L

Weight

~851g

Fabric

100D nylon ripstop, mainly recycled

Water repellency

PFC-free DWR

Rain cover

Integrated and detachable

Hip belt

Removable, padded, with fold-out phone pocket

Back padding

3D EVA foam with air channels

Hydration

Compatible with reservoir systems

Side pockets

Stretch, both sides

Price

Around £110 to £130

The back system and comfort

The back panel is where a daypack lives or dies on a warm day, and the Lithium 25 uses 3D EVA foam moulded with air channels rather than a flat pad. The idea is straightforward: the raised foam blocks sit against your back while the channels between them let air move through, so you get some ventilation without going to a full tensioned-mesh trampoline system.

In practice that means it sits closer to your body than a trampoline back would, which keeps the load stable and close to your spine, at the cost of some of the airflow you would get from a suspended mesh panel. For most UK day walking that is a sensible balance. You are not carrying enough weight in 25 litres to want the load pushed away from your back, and the channelled foam moves enough air to keep you comfortable on all but the hottest, most humid days. If a completely dry back is your single priority, a trampoline-back pack will beat it, but you would lose the close, controlled carry that suits a loaded daypack on uneven ground.

The removable padded hip belt does real work here. It is not a token strap: it is padded enough to take the load off your shoulders and onto your hips, which is what you want on a long day. Being removable, you can strip it off for lighter or more casual use.

Features that set it apart

This is where the Lithium 25 earns its keep. For a 25-litre pack, the feature list is unusually deep.

The integrated, detachable rain cover is the headline. It lives in its own pocket and pulls out to cover the whole pack when the weather turns, which in the UK it reliably will. Having it built in rather than as a £20 afterthought is a real value point, and it is one of the things that justifies the price against cheaper packs that leave you buying a cover separately.

The removable hip belt carries a fold-out smartphone pocket, which is a smart touch. It keeps your phone secure and to hand on the move without digging into the main compartment, and it folds away when you do not need it. Combined with the stretch side pockets, which take a one-litre bottle each and stay accessible on the move, you can keep the things you reach for repeatedly out of the main bag entirely.

The pack is hydration-system compatible, so if you prefer a reservoir over bottles you can run one internally and route the hose over the shoulder. The 100D nylon ripstop fabric is made mainly from recycled materials and treated with a PFC-free DWR, which is the direction the whole industry is moving and good to see on a pack at this level. It sheds light showers on its own and leaves the rain cover for proper downpours.

Weight vs features

At around 851g the Lithium 25 is not light for its size, and it is worth being clear about why. That weight is the rain cover, the padded removable hip belt, the moulded 3D foam back and the extra pockets. Strip those away and you would have a lighter pack, but you would also have a plainer one.

For day hiking, I think that is the right call. You are not covering the distances where 200 grams on your back changes your day, and the features you get for the weight are ones you will actually use: the rain cover on a wet Dorset afternoon, the hip belt on a long climb, the phone pocket every time you stop to check the map. Ultralight thinking belongs on multi-day fastpacking trips, not on a Saturday day walk. For a bigger picture of where this sits, our best hiking daypacks guide lines it up against lighter and simpler rivals.

What fits in 25 litres

Twenty-five litres is the sweet spot for a UK day walk in three seasons. It is big enough for a full day's kit without tempting you to overpack. On a typical day the Lithium 25 will take:

• A waterproof jacket and a spare insulating layer
• Food for the day, plus snacks
• Water, either bottles in the stretch side pockets or a reservoir inside
• A first aid kit, hat, gloves and sunglasses
• Phone in the hip-belt pocket, plus a small power bank and head torch

That all goes in comfortably, with the rain cover already stowed in its own pocket so it never eats into your packing space. For a winter day where you are carrying more insulation and a flask, 25 litres starts to fill up, but for spring-to-autumn walking it is exactly the right size. The organisation is what makes it feel bigger than the number suggests: because the small stuff lives in the side and hip pockets, the main compartment stays clear for the bulky layers.

Pros and cons

• Integrated, detachable rain cover included as standard
• Removable padded hip belt with a fold-out smartphone pocket
• 3D EVA foam back with air channels for close, stable, ventilated carry
• Recycled 100D ripstop fabric with a PFC-free DWR finish
• Deep feature set and organisation for a 25-litre pack
• Swiss build quality from a brand with real alpine pedigree

• Not lightweight at around 851g
• Premium price of around £120
• Channelled-foam back ventilates less than a full trampoline-mesh system

Verdict

The Mammut Lithium 25 is a daypack for people who want their kit sorted. It gives you more features and organisation than almost anything else at 25 litres: an integrated rain cover, a padded removable hip belt with a phone pocket, a ventilated 3D foam back and stretch pockets, all built from recycled ripstop by a brand that has been making mountain gear since 1862. It is not the lightest pack at the size, and at around £120 it is not the cheapest, but the weight and the price both buy you something real.

If you count grams above all else, buy a simpler, lighter pack and accept the shorter feature list. If you would rather carry a well-made pack that handles the details for you, and you do not mind paying premium money for Swiss build quality, the Lithium 25 is one of the best-equipped 25-litre daypacks on the market and an easy one to recommend.

Brand guide: for the full story on the Swiss brand behind this pack, read our Mammut brand review.

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