There will be many occassions in the hills when you need to travel light but need to stay out overnight. Sleeping under the stars sounds so romantic, but if the stars are hidden behind the storm clouds, it can be rather different. To protect you from the elements without incurring much weight or bulk you will need either a lightweight sleeping bag and mat or a duvet jacket for the hardiest of north wallers, but everyone should have some sort of wind and water protection and that means for most a bivvy bag and again for the daring extreme alpinists a bothy shelter for places where you can't lie down.
As well as planned pauses of inactivity in the hills there is also the emergency to consider. If you get caught out by weather, injury or navigational mishap, a day stuck in one place or a night on the hill can either be minor inconvenience or a life-threatening situation. Once again you should protect yourself with a survival bag or bivvy bag.
Survival bags tend to be non-breathable plastic bags that are fine for emergency use for a few hours at a time, but you will find that gradually everything inside begins to get wetter and therefore they can eventually cause problems with chilling of casualites although not as much as if you didn't have one at all.
Bivi bags or bivvy bags are breathable to one degree or another which means they can be used for emergency use with a higher degree of comfort and for longer periods than a survival bag. The lighter less breathable options are ideal for single night use such as on an Alpine route, we favour the Rab Survival Zone here, whilst the most breathable can be used for multiple nights out in all kinds of weather. The latter category fall into 2 types, hooped and unhooped. The unhooped style provides a simple but inpenetrable layer between you and the elements like the Rab Ascent Bivi whilst the hooped style are half way houses between bags and tents and so give a more comfortable sleep and better ventilation, but tend to weigh more and be bulkier.
The Ascent bivi from Rab is highly breathable thanks to its eVent fabric helping prevent overheating. The Ascent bivi comes in a water resistant stuffsack so your bivi will stay dry even if your pack gets wet.Perfect for trek & travel / mountain walking / alpine climbing Deployed size: 2250mm x 700mm Weight: 625g 3 layer 40d eVent fabric 10000mm H/H laminated nylon waterproof bathtub base U-shaped zip opening with removable mosquito net Side walls help maximise sleeping bag loft Glow in the dark zip pullers Supplied in waterproof roll-top stuffsack
A bivy crammed with neat features to make it stand outAscentshell 3L 100% nylon 20D ripstop upper 100% nylon 40D ripstop with TPU floor Dimensions: 82" x 26" x 17" Weight: 596g
The Ridge Raider is a lightweight, waterproof single-person bivi. Coming in at less than 1kg, it is designed for solo mountain use.Size: 2150 x 800mm base, 600mm height Weight: 980g Lightweight single hoop bivi shelter Highly breathable Exchange Lite eVent fabric 10000mm laminated nylon waterproof bathtub base Side walls maximise sleeping bag loft Internal pitch Easton pole Mosquito net door