A bivvy bag is essentially a big waterproof sack that is large enough to sleep in (with a sleeping bag and a small amount of luggage). They are typically carried by outdoorsy people to use as an emergency shelter.
Bivvy bags are made of Gortex these days so it's possible to go to sleep with the bag zipped up over your head. Even though the bag is made of Gortex (a waterproof but breathable fabric) being completely sealed up inside can be a rather claustrophobic experience - apart from anything else, there isn't quite enough space to move around inside. It's quite possible to wake up in the night, and, not immediately realising where you are, to find yourself in pitch blackness in what seems like a straight-jacket. Even though the ensuing blind panic subsides when you realise where you are, you are pitched into new heights of frenzied terror when you can't find the zip and you start frantically scrabbling around in the dark, getting hotter and hotter and stuffier and stuffier until ohmygodyesthatsit you find the zip and gulp in that cool, sweet, night air. Ahhh.
However, with practice (I spent several nights in my back garden - god knows what the next-door neighbours made of the muffled screams for help) I found that it wasn't too difficult to develop techniques for getting in and out, turning over, reading a book, and even smoking a cigarette (don't try this with bag zipped up!). And once you've got the hang of it, it's wonderful to be able to lie down outdoors and watch the sun set over the sea, or to stare into the inky depths of space on a clear night, and yet be really snug and warm. It's also quite an experience to be inside the bag in a thunderstorm - you can feel the rain crashing down onto your body and yet you stay warm and dry.
A disadvantage is that unlike a tent there is nowhere to put anything inside a bivvy bag. You can stuff your shoes down at the bottom and use your clothes as a pillow, but after that there's only enough space for a few small essentials: your wallet, a torch, and several packets of chocolate biscuits (say).
A particular problem is that there isn't enough room to get dressed or undressed inside the bag which means you have to do it outside. If it has been raining and you're wearing dripping waterproofs it can be a tricky operation getting yourself into the bag while keeping the water out. The technique is to divest yourself of clothing a bit at a time while sliding your freshly exposed dry bits into the bag. The process requires a good sense of balance, a working knowledge of yoga positions, and a robust attitude to nudity. (The latter isn't necessarily a problem given that often the point of the whole bivvy bag thing is to be miles from the nearest soul, although I expect my neighbours were amazed at the sight of me struggling to remove my waterproof leggings while hopping around the back garden in my underpants in the middle of a thunderstorm.)
© Kilgore's Enterprises February 1997