Sea to Summit Ultra-Sil Daypack 20L Packable Backpack

The Sea to Summit Ultra-Sil Daypack is a 20-liter packable backpack made from 30D siliconized high-tenacity CORDURA nylon. The fabric delivers an exceptional strength-to-weight ratio. Weighing 72 g (2.5 oz), the pack compresses into an attached stuff sack small enough to fit in a jacket pocket, and it is available in three colors: High Rise, Spicy Orange, and Blue Atoll.

Serious Fabric for a Featherweight Pack

The Ultra-Sil Daypack is built from 30D siliconized high-tenacity CORDURA nylon, the same fabric used across Sea to Summit's dry bags and compression sacks. The siliconized finish adds surface resistance while the CORDURA yarn construction keeps the weave tight and tear-resistant under load. Bar-tack reinforcement at stress points means the seams and strap attachment zones hold up where lesser ultralight fabrics give out first. For a pack that lives stuffed in a pocket or lashed to a summit kit, that durability-per-gram matters.

Packs Down, Sets Up Fast

The Ultra-Sil Daypack stuffs into its own attached stuff sack, which includes an aluminium carabiner for clipping to a larger pack, a belt loop, or a bike frame. Packed dimensions are 5.5 × 10.2 × 18.6 cm (2 × 4 × 7 in), small enough to fit in a jacket pocket or luggage side pocket until needed. Open dimensions are 48 × 20 × 28 cm (19 × 8 × 11 in), giving a genuine 20-liter interior for a summit push, a grocery run, or a day of sightseeing.

Shoulder Straps Built to Carry, Not Just Exist

The reinforced shoulder straps on the Ultra-Sil Daypack resist bunching under load, which matters when a packable bag is actually being used rather than just carried as a backup. The non-padded shoulder straps put the maximum comfort-carry recommendation at 15 lbs (7 kg), a realistic ceiling for a day's worth of gear, groceries, or summit essentials. A daisy-chain webbing loop and two-way zipper closure round out the carry features.

Features

• 30D siliconized CORDURA nylon: high-tenacity fabric with bar-tack reinforcement at stress points
• 20L capacity: open dimensions 48 × 20 × 28 cm (19 × 8 × 11 in)
• Attached stuff sack with aluminium carabiner: packs to 5.5 × 10.2 × 18.6 cm (2 × 4 × 7 in)
• Reinforced shoulder straps: resist bunching; maximum recommended load 15 lbs / 7 kg
• Two-way zipper closure: generous opening with daisy-chain webbing loop

Specifications

Who This Is For and Isn't

The Ultra-Sil Daypack suits hikers, travelers, and cyclists who want a capable 20-liter backup pack that disappears into a pocket or bag when not in use. It works well as a summit pack on multi-day trips, a sightseeing daypack, or an impromptu grocery carrier on foot or by bike, in any situation where a full-size daypack would be overkill.

The Ultra-Sil Daypack is not waterproof: the seams are unsealed and the zipper is not waterproof, so contents will get wet in sustained rain. The non-padded shoulder straps and 15 lb / 7 kg maximum recommended load make it unsuitable as a primary pack for heavy or technical loads. Buyers who need a lighter, more compact option should consider the Ultra-Sil Nano Daypack (18L, 30g, 15D fabric), which is a separate product.

Common Questions

How much does the Ultra-Sil Daypack weigh, and how small does it pack?

The Sea to Summit Ultra-Sil Daypack weighs 72 g (2.5 oz) and packs into its attached stuff sack to a packed size of 5.5 × 10.2 × 18.6 cm (2 × 4 × 7 in), compact enough to fit in a jacket pocket, a purse, or a luggage side pocket.

Is the Ultra-Sil Daypack waterproof?

No. The Ultra-Sil Daypack is water-resistant but not waterproof. The fabric itself resists water, but the seams are not sealed and the zipper is not waterproof, so contents can get wet in sustained rain. A few minutes of light rain is generally fine; a downpour is not.

How much weight can the Ultra-Sil Daypack carry comfortably?

The maximum recommended load for comfortable carry is 15 lbs (7 kg). The shoulder straps are reinforced to resist bunching but are not padded, so loads beyond that threshold will become uncomfortable on longer carries.

What is included with the Ultra-Sil Daypack?

The Ultra-Sil Daypack includes an attached stuff sack and an aluminium carabiner. The carabiner can be used to clip the packed daypack to a larger pack, a belt loop, or a bike frame when not in use as a standalone bag.

How does the Ultra-Sil Daypack differ from the Ultra-Sil Nano Daypack?

The Ultra-Sil Daypack offers 20L capacity, weighs 72 g (2.5 oz), uses 30D CORDURA nylon, and includes adjustable shoulder straps, a daisy-chain webbing loop, and a two-way zipper. The Ultra-Sil Nano Daypack is a separate product with 18L capacity, weighs 30 g (1 oz), uses lighter 15D fabric, and packs down to roughly the size of an egg, making it the better choice when minimum weight and packed size are the priority.