Down vs Synthetic Sleeping Bags: Which Is Right for NZ Camping?
Written by the Dwights Outdoors team — specialists in camping and hiking gear since 1979.
It's one of the most common questions we get at Dwights: "Should I go down or synthetic?" And it's a fair one to be confused about — especially in New Zealand, where you can start a tramp in sunshine on the Kepler and finish it soaked through on the Routeburn. The answer isn't always obvious, and a lot of the advice online is written for somewhere else entirely.
NZ conditions throw up specific challenges: high humidity on the West Coast, rapid weather changes in the alpine, condensation inside DOC huts, and river crossings that leave your pack damp whether you like it or not. Getting the wrong bag doesn't just mean a cold night — it can mean a genuinely miserable (or dangerous) one.
This guide cuts through the noise. We'll give you an honest comparison, cover the real NZ-specific trade-offs, and point you to the right bag from our range for your style of tramping.
Quick Answer: Which Should You Choose?
Choose down if: you're a serious tramper doing multi-day alpine routes, you prioritise warmth-to-weight and packability, you're willing to invest in a quality bag and look after it, and you're camping in relatively dry conditions (think Nelson Lakes, Fiordland alpine, or Canterbury high country).
Choose synthetic if: you're car camping, doing short overnight trips, tramping in consistently wet conditions (West Coast, Fiordland valley floors), buying a first bag for a kid, or working with a tighter budget. Synthetic also makes sense as a hut bag or emergency spare — somewhere it might get damp and you need it to perform anyway.
The Full Comparison
Warmth-to-Weight Ratio
Down wins — and it's not close. A quality down bag packs significantly more warmth per gram than any synthetic equivalent. This matters most when you're carrying a bag over a multi-day route. The One Planet Bush Lite, for example, gives you serious alpine warmth at a weight that won't wreck your knees. A synthetic bag offering the same rated temperature will be noticeably heavier and bulkier. If you're gram-counting, down is the obvious choice.
Moisture Performance
This is where synthetic earns its place — and where we'll be honest about down's weakness. When down gets wet, it loses loft (and therefore warmth) dramatically. It's also slow to dry. Synthetic insulation retains a meaningful portion of its warmth even when damp, and dries much faster.
The gap has narrowed with treated down (hydrophobic down). Most premium bags — including the Rab Neutrino Pro and One Planet's higher-end range — use water-resistant down that handles light moisture and condensation well. But in genuinely saturated conditions, synthetic is still the safer choice. If your sleeping bag ends up at the bottom of a flooded pack on the West Coast Wilderness Trail, you'll be grateful for synthetic.
Packability
Down compresses far smaller than synthetic. A high-fill-power down bag will squeeze into a stuff sack roughly half the volume of an equivalent-warmth synthetic bag. For a dedicated tramping kit where space matters, this is significant. Synthetic bags are bulkier — fine for the boot of a car, less ideal for a 65L pack on a six-day trip.
Durability
A well-cared-for down bag will outlast synthetic by years — sometimes decades. Premium bags from One Planet and Rab are built to last. Synthetic insulation degrades faster with repeated compression and washing. That said, synthetic is more forgiving of rough use — it won't clump or develop cold spots the way neglected down can.
Price
Synthetic is cheaper up front, full stop. Our synthetic range starts under $130 (Dwights Thermoshell -8) and tops out around $259 (One Planet Sac). Down bags start at $499 (One Planet Nitrous) and go well north of $1,000 for alpine-grade kit. If budget is the deciding factor, synthetic gets you a functional sleeping bag without the investment. If you're committed to tramping long-term, a quality down bag pays back over time.
Care
Down needs more attention. It must be stored uncompressed (hanging or in a large cotton bag), dried thoroughly after every trip, and washed properly with a specialist cleaner — stuffed in a pile in the corner of a garage is how you ruin a $700 bag. Synthetic is more forgiving: wash it, stuff it, use it. If you're not ready to look after a down bag properly, that's worth factoring in.
NZ-Specific Conditions: What Actually Matters Here
West Coast & Fiordland Valley Floors
The West Coast gets around 5–8 metres of rain per year in some spots. If you're tramping here, assume your gear will get damp. Hydrophobic down helps, but for extended trips in this region, a synthetic bag or a dry bag that genuinely seals (not just a stuff sack) is the pragmatic call. At minimum, triple-bag your sleeping bag inside your pack.
Alpine NZ (Canterbury, Otago, Nelson Lakes)
The drier side of the Main Divide changes the calculus. Alpine starts tend to involve cold, clear nights and low humidity — exactly the conditions where premium down performs at its best. If you're doing hut-to-hut routes in the South Island high country, a quality down bag is the right tool.
DOC Huts & Condensation
DOC huts can be surprisingly damp environments — wet gear hanging inside, multiple people breathing all night, poor ventilation in older huts. Condensation on the inside of walls, or from a wet tramper climbing into a bunk next to you, can transfer moisture to your bag. A hydrophobic-treated down bag handles this reasonably well, but it's worth airing your bag out whenever you get the chance. If you're doing popular Great Walks with consistently full huts, synthetic's moisture tolerance is a genuine advantage.
River Crossings
Unplanned swims happen. Pack your sleeping bag inside a waterproof liner — not just a stuff sack — regardless of whether it's down or synthetic. This isn't paranoia; it's standard NZ tramping practice.
What We'd Recommend From Our Range
Browse our full sleeping bag collection — here's where we'd point different trampers. Our three best-selling down bags are the One Planet Nitrous, Sonder, and Cocoon; between them they cover most serious trampers from three-season entry through to high-country alpine.
Best for Serious Alpine Tramping
One Planet Bush Lite ($849–$1,019) — A true four-season NZ alpine bag. High-fill-power down, a fit that actually works for wide-shoulder NZ body types, and built to last. If you're doing remote hut routes and multi-day alpine traverses, this is the bag we'd buy ourselves.
Rab Neutrino Pro ($1,091) — Rab's expedition-grade construction with hydrophobic down and outstanding warmth-to-weight. For trampers who push into genuinely cold and committing terrain.
Rab Expedition 1000 — The serious end of Rab's range. Built for high-altitude and sustained cold — when conditions stop being uncomfortable and start being dangerous.
Best Mid-Range Down Bag
One Planet Cocoon or Sonder ($599–$699) — The sweet spot for most serious trampers, and two of our best sellers for good reason. Three-season to light four-season warmth, quality down, and a price point that's high enough to get the good stuff without tipping into expedition territory. If you're doing regular multi-day tramps and want a bag that'll last years, start here.
Best Entry-Level Down
One Planet Nitrous ($499–$549) — The entry point to quality down, and consistently one of our top sellers. Solid three-season performance, genuine down warmth, and a step up from anything in the synthetic range in terms of packability and weight. If you're new to down bags and want to invest in something that'll grow with your tramping, the Nitrous is where we'd start.
Best for Quilters
One Planet Quest Pro Quilt ($449–$479) — If you're a stomach or side sleeper who finds traditional mummy bags restrictive, the Quest Pro Quilt is excellent. Pairs well with a good sleeping mat.
Best Synthetic for Car Camping & Family Weekends
Dwights Thermoshell -8 ($129.99) — When size and weight aren't the priority — like car camping or family weekends — the Dwights Thermoshell is hard to beat. Genuinely warm (-8 rated) at a price that makes sense. This is our go-to recommendation for anyone who wants a reliable, cold-rated synthetic without overthinking it.
Best Premium Synthetic
One Planet Sac ($259) — The top of our synthetic range. More warmth and better build quality than budget synthetics, and honest wet-weather performance. Worth it if you're tramping seriously in damp conditions and synthetic is the right call for your environment.
Best for Kids
Dwights Kids Thermopod ($119.99) — Kids grow fast and get their sleeping bags filthy. Our own house-brand kids' bag is solid, warm, and built for that reality. A reliable synthetic kids' bag makes a lot more sense than putting a child in an expensive down bag they'll outgrow in two seasons.
Common Mistakes to Avoid
- Storing a down bag compressed. The fastest way to destroy loft. Always store down bags loosely — hang them or use a large storage sack.
- Buying a down bag for West Coast conditions without a proper waterproof pack liner. Hydrophobic down is not waterproof down. Plan accordingly.
- Choosing a temperature rating that's too optimistic. ISO comfort ratings are calculated for average adult women — men often run warmer, but everyone's different. If you sleep cold, size up. A warm bag you don't use is less dangerous than a cold bag you're relying on.
- Neglecting to dry your bag after every trip. Even if it doesn't feel wet, condensation accumulates. Hang it out before storing, every time.
- Buying the cheapest synthetic bag for a serious tramp. Budget synthetics are fine for car camping. For multi-day tramping in cold conditions, cut elsewhere in your kit before cutting on your sleeping bag.
- Ignoring pack liner setup. Stuff sacks aren't waterproof. A dry bag or a rubbish bag liner inside your pack is cheap insurance.
Frequently Asked Questions
Is down or synthetic better for NZ conditions?
It depends on where you're going. For the drier alpine regions — Canterbury, Otago, Nelson Lakes — quality down is hard to beat. For consistently wet environments like the West Coast or Fiordland valley floors, synthetic is more forgiving. Many experienced NZ trampers own both and choose based on the trip.
How do I keep a down sleeping bag dry in NZ?
Use a waterproof pack liner (not just the stuff sack) inside your pack. Most premium down bags now use hydrophobic-treated down, which helps with light moisture and condensation — but that's not a substitute for keeping the bag dry. A dry bag rated for kayaking works well as a bag liner.
What fill power should I look for in a down sleeping bag NZ?
For serious tramping, 700+ fill power is a useful benchmark. Higher fill power means more warmth per gram of down. The One Planet and Rab bags in our range sit in the 700–850 fill power range — genuinely good insulation, not entry-level fluff.
Can I wash my down sleeping bag?
Yes, but carefully. Use a front-loading machine (no agitator), a specialist down wash, and a low heat setting in the dryer with a couple of clean tennis balls to break up clumps as it dries. Never dry-clean a down bag. When in doubt, take it to a gear specialist.
Are synthetic sleeping bags worth it, or should I just save up for down?
For car camping, kids' bags, or tramping in wet conditions, synthetic is absolutely worth it on its own merits — not just as a cheap down alternative. If you're doing serious multi-day tramping in drier alpine conditions and plan to do it for years, saving for quality down is usually worth it long-term.
What's the difference between a sleeping bag quilt and a standard mummy bag?
A quilt (like the One Planet Quest Pro Quilt) eliminates the insulation underneath you — which is compressed by your body weight and not doing much anyway — saving weight and bulk. You pair it with a good sleeping mat for ground insulation. It's a smart system for experienced trampers who sleep well and move around in their sleep less. Mummy bags are more beginner-friendly and better in very cold conditions where you might need to cinch down the hood.
Still Not Sure?
The best sleeping bag is the one that matches your conditions, your trip style, and your budget — not the most expensive one, and not the most popular one. Browse our full sleeping bag range at Dwights, or check out more guides in our sleeping bag blog to go deeper on specific topics.
If you're still unsure, get in touch. We've been helping NZ trampers choose gear since 1979 — we're not going to steer you wrong.