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Hyperlite Mountain Gear Southwest 3400
#4 — Best Ultralight Waterproof Backpack

Hyperlite Mountain Gear Southwest 3400 Review (2026)

A fully Dyneema pack built like a roll-top dry bag, at under 2 pounds

★★★★☆
9.3/10
Reviewed by William • Updated July 2026 $379

Hyperlite Mountain Gear was founded specifically because its founder couldn't find sufficiently durable ultralight gear on the market, and the Southwest 3400 is the clearest expression of that mission — a pack built almost entirely from Dyneema Composite Fabric, genuinely waterproof rather than merely water-resistant, all at under 2 pounds. The roll-top closure works like a dry bag, and the solid (non-mesh) Dyneema Hardline exterior pockets specifically target hikers moving through abrasive canyon and brush terrain where a mesh-pocketed pack would quickly wear through.

TrailCraft Score

What Works

  • Fully Dyneema construction is genuinely waterproof, not just water-resistant, thanks to the roll-top dry-bag-style closure
  • Solid exterior pockets (versus the Windrider's mesh) hold up better against abrasive terrain like canyon walls and dense brush
  • One of the most trusted names in ultralight packs, made entirely in Maine since 2010

Limitations

  • At $379-425 depending on size, it's one of the most expensive packs in the ultralight category
  • No back-length adjustability or padded suspension — comfort is basic by design

Specifications

Weight32 oz / 2 lb
Capacity55L internal + 9.8L external
Max Recommended Load40 lb
Fabric100% Dyneema Composite Fabric
ClosureRoll-top, dry-bag style
Made InUSA (Maine)

Score Breakdown

Weather Resistance
9.6
Durability
9.3
Weight
9.2
Comfort
8.4

What Sets It Apart

Hyperlite Mountain Gear was founded specifically because its founder couldn't find sufficiently durable ultralight gear on the market, and the Southwest 3400 is the clearest expression of that mission — a pack built almost entirely from Dyneema Composite Fabric, genuinely waterproof rather than merely water-resistant, all at under 2 pounds. The roll-top closure works like a dry bag, and the solid (non-mesh) Dyneema Hardline exterior pockets specifically target hikers moving through abrasive canyon and brush terrain where a mesh-pocketed pack would quickly wear through.

The tradeoff for that extreme weight and durability focus is comfort: there's no padded suspension or back-length adjustment, so the pack works best for those already comfortable carrying loads under 40 pounds without heavy structural support.

A fully Dyneema pack built like a roll-top dry bag, at under 2 pounds

Who This Is For

The Southwest 3400 is right for: thru-hikers on trails with real weather exposure who want genuine waterproofing rather than water resistance, hikers in abrasive canyon or brush terrain who need solid (not mesh) pocket fabric, and anyone willing to trade suspension comfort for the lowest possible weight in a genuinely durable pack.

A note on pricing and links: Prices are current as of July 2026. Some links are affiliate links.

How It Compares

See the full comparison

All 20 best ultralight gear in this category ranked side by side.

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Common Questions

Is the Southwest 3400 actually waterproof?
Yes — the fully Dyneema Composite Fabric construction with a roll-top, dry-bag-style closure is genuinely waterproof, not just water-resistant, which is a meaningful step up from most ultralight packs that only claim water resistance.
What's the difference between the Southwest and Windrider versions?
They share the same core design, but the Southwest uses solid Dyneema Hardline exterior pockets for durability in abrasive terrain, while the Windrider uses mesh pockets that dry wet gear faster but wear through more easily on rough surfaces.
Is the Southwest 3400 comfortable for heavy loads?
It's rated for up to 40 lb, but it lacks the padded suspension and adjustability of framed packs like the ULA Circuit, so comfort at the upper end of that range depends more on the wearer's load-carrying experience than the pack's structure.