A bivvy is like a condom for a sleeping bag ensuring, even if sleeping in a puddle in torrential rain, waking dry and warm is a sure thing.
Sleeping on wilderness islands or remote cliff tops and beaches often means, in summer, it’s easier to travel light and to travel without a tent. In wooded areas this is never a problem as a hammock tied between two trees with an A-frame tarp over the top is more than enough protection from the worst of storms.
However, there are often no trees at all on Hebridean islands and the answer is to make camp using the hull of a kayak, a tarpaulin, paddles as tent posts and guy ropes and tent pegs to make taught and secure the lot. A ground sheet and sleeping bag does the rest.
A bivvy bag enables the expeditioner to do away with the lot if necessary – it is a waterproof cover for a sleeping bag enabling the camper to sleep out with no tent or tarp. I’ve heard it accurately described as a raincoat for your sleeping bag. It is cheaper, lighter, more discreet and quicker to set up and take down than a tent.
It is important to use a breathable bivvy bag and the best I have seen is the British Army Gore-Tex bivvy. It’s kit like this that famously enabled the Royal Marines to yomp 90 km in three days carrying 80-pound loads across the arctic Falkland tundra to recapture Port Stanley. The same venture with tents added to this load would not be possible.
Rab’s Pertex Shield Survival Zone bag costs twice as much and does the same thing but, if it’s important for you to save three ounces in weight by having tapered ankles and half the foot space as a result, this is your one. It’s very pretty in red.