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Sea to Summit Ultra-Sil Day Pack Review

A bare-bones ultralight pack for those really dedicated to cutting ounces
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Price:  $40 List | $35.17 at Amazon
Compare prices at 3 resellers
Pros:  Insanely light, packs up super tiny, fits slightly larger people
Cons:  Nearly no features, only one big pocket, super thin fabric, can feel contents
Manufacturer:   Sea to Summit
By Maggie Brandenburg ⋅ Senior Review Editor  ⋅  May 14, 2019
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54
OVERALL
SCORE


RANKED
#11 of 12
  • Comfort - 25% 3
  • Versatility - 25% 5
  • Weight - 25% 10
  • Ease of Use - 15% 4
  • Durability - 10% 3

Our Verdict

The Sea to Summit Ultra-Sil is an impressively small, lightweight pack that minimalists are sure to love. For just a couple of extra ounces, you can clip this packed up pack just about anywhere and be adventure-ready. A super thin design keeps this bag reasonably comfortable and by removing nearly every extra feature, the Ultra-Sil is the lightest pack we tested. This loss of organizational pockets and use of thinner fabric cuts into the versatility and durability of this bag a bit.

Compare to Similar Products

Our Analysis and Test Results

The Sea to Summit Ultra-Sil is the smallest, lightest daypack we reviewed. Sea to Summit used 30D ripstop nylon and cut out all padding to make this pack weigh just 2.7 ounces.

Performance Comparison



If you're a fan of the ultralight  the Ultra-Sil might be the right pack for you.
If you're a fan of the ultralight, the Ultra-Sil might be the right pack for you.

Comfort


For a pack that has literally no padding anywhere, this pack is… well, not comfortable unless you pack it right. It has no hip belt or load lifters or sternum strap, and the shoulder straps are padding-less. They do, however, have a very flat, ergonomic design that helps them to hold up this bag without digging into your shoulders. And though they claim this bag can hold 250x its own weight or over 40 pounds, we wouldn't recommend it for any length of time. The Ultra-Sil requires careful packing to stop from feeling every edge and corner from digging into your back. We found that this pack and other ultralight packs we tested are similar in overall comfort, though they take slightly different approaches to achieve that - rather than using some minimal padding in the shoulder straps, Sea to Summit chose a wide, ergonomic design with no padding.

These straps have no padding whatsoever  but their width helps distribute the weight across your shoulders.
These straps have no padding whatsoever, but their width helps distribute the weight across your shoulders.

Versatility


A lot of a pack's versatility hinges on the usefulness of its features, which the Ultra-Sil is lacking a lot of. This bag is just one zippered pocket and that's about it. There's a tiny loop on top you could clip something to and three fingers-worth of daisy chain on the bottom. If you really want to get inventive (and we bet you do, you ultralight enthusiast!), the tiny stuff pouch that ends up inside the pack could double as a little pocket for your keys. It also comes with a carabiner, which can then be used to attach something to the outside of the bag while it's in use. Other ultralight models retained a few extra pockets that we think make them more useful and versatile than this one.

One of the few features that this bag has - three loops of daisy chain near the bottom for clipping on  a bike light or attaching a whistle.
One of the few features that this bag has - three loops of daisy chain near the bottom for clipping on a bike light or attaching a whistle.

Weight


It's hard to beat a bag that only weighs 2.7 ounces (carabiner included). Even the other ultralight models we tested weigh more, though barely. This weight reduction does come at the cost of those extra features and key areas of padding. But if weight is paramount, the Ultra-Sil is the lightest we tested.

The Ultra-Sil (bottom right) is the smallest pack we reviewed.
The Ultra-Sil (bottom right) is the smallest pack we reviewed.

Ease of Use


The Ultra-Sil is extremely simple. At 20 liters of capacity, it has just one large compartment that zips wide open for easy access. It's also easy to lose one small item in just one large compartment, as we discovered. This pack is also without any zipper pulls, which cuts weight, but we found ourselves missing them, as the zipper tabs are incredibly short.

One area in which the Ultra-Sil has a slight advantage over other ultralight models we tested, is the size of person it can accommodate. With slightly longer shoulder straps, this pack is easier for taller and larger folks to wear.

Just one big pocket - though you could be crafty and use the stuff sack as a tiny pocket too!
Just one big pocket - though you could be crafty and use the stuff sack as a tiny pocket too!

Durability


Made of 30D ripstop nylon, this pack is the thinnest we tested. Even other ultralights are thicker (though marginally so). That being said, we had no actual issues with this bag during our months of testing. That doesn't mean we'd recommend it as your primary bag to hike through a thorny ecosystem though. If you like lightweight, but don't want to sacrifice quite so much in fabric durability, you might consider some of the other lightweight, simple packs we tested that only weigh a few ounces more.

30D ripstop nylon is quite thin  even on the reinforced shoulder straps.
30D ripstop nylon is quite thin, even on the reinforced shoulder straps.

Value


This pack is one of the cheapest we reviewed. For how versatile and portable it is, we think this is a great value. And hey, if you do rip an unfixable hole in that 30D nylon, replacing the whole bag at this price isn't quite so painful.

Turn any chance outing into an adventure by keeping an ultralight pack on your person.
Turn any chance outing into an adventure by keeping an ultralight pack on your person.

Conclusion


We appreciate the lengths Sea to Summit has gone to, to create this ultralight, super packable bag that just works. It's not one to load up with heavy or pointy objects or take on a long day out. Though we ultimately like the features included in slightly heavier ultralights just a little bit more, for an on-the-go bag, this one's pretty handy too.

The lightest pack we tested  the Ultra-Sil can come with you just about anywhere.
The lightest pack we tested, the Ultra-Sil can come with you just about anywhere.

Maggie Brandenburg