Bivvi Bag Basics

Submitted by Lauren on 1st August 2018

A Bivvi (or Bivy, Bivvy, Bivi etc.) bag, is a waterproof bag that fits around your sleeping bag so that you can sleep outside without the need for a tent. It acts as both a groundsheet and cover for your bed. In the past they were mostly used by the army for fast and light travel, but they’ve become a lot more popular among civillian campers in recent years, particularly ultralight hikers and wild campers.

Bivvis come in all shapes and sizes, from the barely there water ‘resistant’, to the unweildy emergency shelter, to the nearly-a-tent type with hoop, pegs and insect net. Some people use them alone, others pair them with a tarp to keep off the worst of the rain. I’ve learnt to love the simplicity of a bivvi, and waking up to see the stars or the sunrise right in front of me makes up for any of the disadvantages.

View from a bivvi

Bivvi Pros

Lightweight – No need for guylines, poles, flysheets and porches, swapping a tent for a bivvi is the ultimate way to save weight and space in your bag
Quick – just shove your sleeping bag inside and you’re done. You can even pack your bedding inside the bag to transport it ready assembled. In the morning just let the air out of your sleeping mat and roll the whole lot up from the bottom.
In touch with nature – As Alastair Humphreys said, a tent is just “a cramped, damp, flappy, lumpy version of home”. In a bivvi, you wake up under the stars, with dew covered grass inches from your face. You really are outside.
Discrete – If you find a tussock or a hedge to sleep by, you become virtually invisible, which makes sneaky wild camping easy, and if you are ever moved on (NB: I’ve never actually known anyone to be moved on while sleeping out) you can pick up and go without unpegging or wrangling poles.
Cheap – starting at around £20, there’s no excuse not to give them a go

Bivvi Cons

Damp – If it rains, you can usually tighten the hood, or retreat under a bush or tarp, but you’re always going to get more damp than you would in a tent. And even on warm dry days, you’ll still likely suffer some condensation inside the bag from the moisture your own body gives off during the night. It’s never really bothered me, but could get trying after several damp, cold nights
Public – it’s one thing on a deserted moorland, another in a campsite. You’ll be doing a dance in your bag to change your undies
Not great for fidgets – I’m a restless sleeper, and on several occasions I’ve woken up to find my sleeping mat, bag and bivvi have ended up in the most horrible tangle in the night

My setup

Bivvi bag, Sleeping bag, tarp and pillow

The bivvi I use is an Alpkit Hunkka XL. It’s light and small, and packs away easily into its own stuff sack.

Just like sleeping in a tent you’ll need a mat. I most often use my Sea to Summit Ultralight air mattress, so I put it inside my bivvi to give it a bit of protection from the ground. I have also used my Thermarest SO-Lite and have left that outside the bag. The benefit there is that when it starts to get cold in the evening, you can get into your bivvi and sit up in it, like a snug caterpillar! On the downside, I tend to roll off in the night and wake up on the cold lump ground…

On top of the mat and inside the bag goes my sleeping bag. I have a few of these now, but the one I use most for wild camping is my OEX Leviathan. It’s light, packs small and is toast warm well below zero.

I like a bit of luxury when I sleep, so I take an inflatable pillow which slips under the hood of my sleeping bag, inside the bivvi.

If the weather is looking dodgy I often pair my bivvi with a tarp. It lets me leave my stuff a bit more spread out, and I don’t have to worry about my face getting wet in the night! I use a lightweight Rab Siltarp2 which is big enough to totally enclose me if I want. Paired with 4 titanium pegs, some cord, and my walking poles I can turn it into any sort of shelter that fits me and my gear very quickly. My sitmat and a bin liner work in very wet weather as enough of a groundsheet to stop the entrance getting muddy, and I’m able to make a cosy shelter in a few minutes of arriving at my campsite. If I’m wild camping I’ll either just use the tarp as a lean-to and tie one side to trees or a wall, or forego it entirely and simply sleep under a thick hedge! In a camp site I’m likely to make more of it, giving me a little privacy and more of an area to call mine. The beauty of a tarp though is how flexible it is, and if a forecast has changed during my stay I can just alter the pitching angle to increase the rain protection or ventilation.

My gear and shoes either go in to a garden waste sack or my bivvi if it’s going to rain, or just sit outside next to me.

Tarp for the rain

Bivvi buying options

There are hundreds of bivvis out there, all with their own benefits, and it’s hard to know where to start. There are several key factors to think about:

Waterproof-ness – Bags are measured in hydrostatic head (HH). Low numbers mean it’s less waterproof. How much water it’ll let out (breathabilty) is also a factor here, and helps avoid the internal condensation I mentioned above.
Weight – How far do you want to carry it? Don’t forget, lightweight bags are often less waterproof, so you might have to make a trade there
Hooped or not – A hoop keeps the plastic off your face and gives you a little more space, but increases the size and weight of your bag and stops it being quite as simple to set up
Closure – Do you want it to open like a sleeping bag, or are you ok wriggling in from the top? And what about the facehole – is a drawstring going to do the job or do you want an insect net to keep you protected, or a face cover so you can totally enclose yourself in the bag?
Size – How big are you, and do you want to get a large sleeping mat into the bag? What about your pack? Will that be ok outside or do you want it in the bag with you?

Bivvi on the hillside

In all the discussions about bags I’ve had, 2 bags come up time and time again – the classic army surplus bag, and the Alpkit Hunkka XL. They’re both simple, highly waterproof bags with a basic drawstring hood and no other opening.

Army Goretex bag
These are cheap, bombproof (ok, not quite, but isn’t bothered by brambles and gravel), large, simple and easy to get hold of. They’re the perfect place to start (and for many, finish). The only real con is that they’re heavy, often the best part of 1kg, Which blows away any real benefit to using a bivvi over a lightweight tent.
If you’re not sure if this bivviying thing is for you, and just want to try it once or twice, I’d recommend this bag as an ideal starting point. You can pick these up on eBay and in army surplus stores very easily.
Alpkit Hunkka XL
This is what I use. It’s not far from an army bag, but is made from much lighter fabric and so packs smaller and weighs less. Mine hasn’t shown any signs of damage from use, but I do feel less confident about dragging it through the brambles than I would an army bag. It’s also apparently less breathable, but I can’t say I’ve noticed the difference in practice.
Alpkit do a smaller size of this same bag. I like the large one though, for the ability to get my air mattress inside and my shoes or pack if I want to.

There’s a really detailed breakdown of all the bivvi options out there and their various pros and cons on the Next Challange website – it’s well worth a look before you buy.

I heartily recommend giving a bivvi bag a try. After some initial doubts I’m now a huge fan and have spent a lot of time in mine. It’s always a wonderful way to wake up, and the simplicity of it makes it much more enjoyable than a tent!

View from a bivvi