The Sea to Summit Ultra-Sil Nano Travel Day Pack (MSRP: $29.95, 1 oz / 30 g) is an 18 L (1100 cubic inches) summiting daypack that can be compressed to the size of an egg and tucked into a multiday pack for peak-bagging on longer trips.

A yellow pack on a white background.
The Sea to Summit Ultra-Sil Nano Travel Day Pack. Photo: Sea to Summit


  • 18 L capacity
  • MSRP: $29.95
  • weight: 1 oz / 30 g
  • compresses to roughly egg size
  • 10 lb (5 kg) recommended load capacity
  • 15 denier siliconized nylon fabric
  • asymmetrical zipper to reduce pack size
  • bar-tacks at stress points for added strength

Testing Context

An ultralight summiting pack is a piece of kit that has appealed to me for a while. I’m not usually a big peak bagger on multi-day trips, but the occasion has come up when one would be useful.

I knew I’d be spending a day camped as part of my Corona Ridge adventure, and I wanted to explore the upper reaches of Corona Canyon. The smallest and lightest pocket pack (in one of my preferred brands) is the Sea to Summit Ultra-Sil Nano Day Pack. I was instinctively drawn to this pack’s little lime-sized package. It’s light, compact, and I could picture tossing it into my kit on any trip where I might need a summiting pack. I made the purchase and took it out into the field on a summer excursion deep into a canyon off the North Saskatchewan River’s southern banks. This review is based on my experiences on that trip (and a few others throughout 2020)

This is a first look at new gear that recently entered our review pipeline, and hasn't yet been subjected to rigorous field use. Learn more about the types of product reviews we publish.

First Impressions

Storage Capacity

The Sea to Summit Ultra-Sil Nano Travel Day Pack impressed me with how truly tiny it packed and how much space there was in the pack once unfurled.

a flat layout of the backpacking gear able to fit into the pack - including some jackets, a hat, gloves, sunscreen, a small camera, and a hard-sided water bottle.
I stuff my wishlist of summit supplies into the Sea to Summit Ultra-Sil Nano Daypack and it’s pretty crowded but it all fits.

I could easily fit two down insulating layers (a vest and a sleeved hoodie), a rain/wind shell, a hard-sided Nalgene 1 L bottle, a pair of gloves, a toque (Candian for beanie hat), a Buff, a sun hat, small bottle of sunscreen, my mirrorless camera, and room for snacks.

the uncompressed pack, now filled with gear, rests on the ground. A large lime is next to the pack for scale.
The Sea to Summit Ultra-Sil Nano Daypack stuffed with my supplies and compared to the original lime.

I will note here I wear kid’s size large or women’s extra small so my clothes aren’t as voluminous as those found in many packs.


The Sea to Summit Ultra-Sil Nano Travel Day Pack is a one-compartment pack with a relatively small opening. The more I stuff into the Nano, the less likely it is that I can find anything. I will also note the zipper is light-duty – similar to what you would find on a windbreaker – so stuff with caution my friends.

Sea to Summit made the most of the opening by making it a diagonal slash opening across the top of the pack.

Fit and Comfort

Putting on my well-stuffed Sea to Summit Ultra-Sil Nano Travel Day Pack Nano is comfortable enough, but not something I want to wear for longer than about an hour or two continuously (which is also about as long as most mid-trip peak bags take.) As with any frameless pack, care in packing is crucial.

I’ve also loaned it to other hiking partners while I was off taking photos or doing other things and the rather formless pack fits men about 6 ft (2 m) tall about like it fits me – not perfectly, but functionally.


a woman stands in a mountain meadow with her back to the camera. In the distance, snow-capped mountains and trees.
My foray to the Corona Creek headwaters was an ideal testing ground for the Sea to Summit Ultra-Sil Nano Daypack.
a close up of three items of similar size - a white chicken egg, the compressed backpack, and a large lime.
The compressed Sea to Summit Ultra-Sil Nano Day Pack as compared to a chicken egg and a lime.
A man looks across a wide stream. In the background are rugged mountains and dark skies.
Testing the Sea to Summit Ultra-Sil Nano Travel Day Pack.
a woman's hand holds the compressed pack. It is about the size of an egg or large lime.
Sea to Summit Ultra-Sil Nano Travel Day Pack is easy to throw in a pack when it compresses this small.
A man stands on a log looking out over a meadow.
My partner Michael borrowed the Sea to Summit Ultra-Sil Nano Travel Day Pack for an afternoon of adventuring. The fit is functional.

The Takeaway

The Sea to Summit Ultra-Sil Nano Day Pack is handy to have around, but I do find it uncomfortable after an hour or two. This isn’t unexpected for what is essentially a formless sack of nylon.

I modify the shoulder straps by adding an elastic clip cord (the pad-strap from my Enlightened Equipment Revelation quilt). I also will note that the fabric is light duty and I did manage to puncture a small hole in the ripstop fabric. The hole was easily patched with some Tenacious Tape on the inside and outside of the pack fabric.

I took the Sea to Summit Ultra-Sil Nano Day Pack on my Corona Creek adventure and (a few others throughout 2020) and ten-out-of-ten would bring it again. I’ve started throwing it in my pack if any kind of potential off-piste adventure is expected.

Learn More: Sea to Summit Ultra-Sil Nano Travel Day Pack

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