A portable shelter comes in very handy during multi-day hiking trips as it allows you to set up camp almost anywhere and anytime you like rather than having to reach accommodation facilities such as for example mountain huts. While tents are the most versatile and comfortable, you might find a tent to be too heavy and bulky to carry if you are hiking alone – especially on hiking trips lasting 3 days or less. On such trips bivy sacks are a great alternative to tents as they are lighter while providing similar weather protection. On average, a high-quality bivy sack is twice as light and 30 % smaller (when packed) as a high-quality two-person tent. Besides taking up less space in your backpack, a bivy sack can also be set up very fast if the weather is against you. Bivy sacks are, however, not suitable for longer hiking trips as they provide very limited comfort/space and often require that the backpack is left outside.
In this review we selected and reviewed the best bivy sacks for hiking and mountaineering. We decided to only include bivy sacks made of waterproof/breathable materials as they provide the best versatility in various weather conditions. We were especially looking for lightweight and well-packable products that offer great functionality. All bivy sacks listed in this review can only accommodate one person.
If you are undecided between getting a bivy sack or a hiking tent, you should also check out our selection of the Best Lightweight Hiking Tents. If you want even more minimalistic portable shelter than a bivy sack, check out our review of the Best Lightweight Tarps for Hiking. As for the comfort inside the portable shelter of your choice, we have also made reviews of the Best Sleeping Pads, Summer Sleeping Bags and Best 3-Season Lightweight Sleeping Bags.
1. Buying a Bivy Sack – What is important?
Lightweight hiking equipment allows you to reach your goals faster and easier and as shelters are usually among the heaviest items of hiking gear, a lightweight shelter can make a big difference in the weight that you carry. For example a low-quality one-person tent can easily weigh as much as 2.5 kilograms while a high-quality bivy sack weighs no more than 1 kilogram.
Bivy sacks usually offer just enough space for one person. However, some bivy sacks allow you to suspend the material above the head which reduces the claustrophobic effect of the small shelter and thus increases your comfort. There are two different systems to suspend the material above the head area; the pole system or flexible wire system.
The pole system is very reliable but requires additional work when setting up the bivy sack as the pole has to be inserted in the sleeve and secured.
The flexible wire system is common on bivy sacks that feature a relatively low head height. The wire in the head area stretches automatically when bivy sack is unpacked and thus slightly suspends the material above the head area.
Hikers and mountaineers always strive to have well-packable equipment as it allows them to save space in the backpack for other essentials. In this selection we only included bivy sacks that are small when packed.
All bivy sacks included in this review are made of waterproof/breathable fabrics such as Gore-Tex, eVent and Pertex (same fabrics like rain jackets use). Waterproof/breathable fabrics differ by their waterproof performance, breathability and durability.
3-layer fabrics (consist of a face fabric, membrane and an inner fabric) are very rugged and offer great breathability and rain resistance. Bivy sacks made of 3-layer waterproof/breathable fabrics offer superb performance but are also quite expensive.
2.5-layer fabrics (consist of face fabric, coating or membrane and a non-fabric inner layer) are extremely light and offer decent breathability as well as rain resistance. Bivy sacks made of 2.5-layer waterproof/breathable fabrics are therefore very light but they might occasionally have buildup of condensation due to the mediocre breathability of the fabric. Ventilation holes/areas might be used in order to reduce condensation.
2-layer fabrics (consist of a face fabric and coating or a membrane) are heavier due to thicker individual layers and offer merely inferior breathability and waterproof performance in comparison to 2.5- and 3-layer waterproof/breathable fabrics. Bivy sacks made of 2-layer fabrics are usually only used as emergency shelters – which is why we didn’t include any in this review. They are occasionally equipped with ventilation holes in order to mitigate the condensation issues which can appear due to the poor breathability of the fabric.
To learn more about waterproof/breathable fabrics check out the Hard Shell section in our Comparison of Shell Materials.
Regardless of the number of layers, any fabric used for portable shelters should be treated with DWR (durable water repellant) so that they repel the water rather than absorbing it. The DWR treatment additionally increases the waterproof performance. The floors of bivy sacks are usually made of polyurethane-coated nylon rather than a waterproof/breathable fabric for better durability and water resistance.
Waterproof Performance and Condensation Resistance:
The waterproof performance and condensation resistance of a shelter greatly depend on the fabric. Unfortunately, the two qualities are mutually exclusive to some extent. The higher the breathability of the fabric, the better is the condensation resistance as it allows moisture and warm air to escape to the outside. However, there is no such thing as highly breathable fabric that is also completely waterproof. Therefore, manufacturers have to find the right ratio between the breathability and waterproof performance in order to achieve the best functionality. Bivy sacks in general offer inferior rain and condensation resistance in comparison to double-wall tents (which use completely waterproof fly that comes over a breathable canopy) but on the other hand they are also faster to set up and significantly lighter. We do not recommend using bivy sacks (as well as single-wall tents) in areas that are known for continuous heavy rain.
2. The Best Bivy Sacks Review
- Outdoor Research Alpine Bivy
- Rab Ridge Raider Bivy
- Black Diamond Big Wall Hooped Bivy
- Rab Alpine Bivy
- Outdoor Research Helium Bivy
|Feature/Product||Outdoor Research Alpine Bivy||Rab Ridge Raider Bivy||Black Diamond Big Wall Hooped Bivy||Rab Alpine Bivy||Outdoor Research Helium Bivy|
|Packed Weight||907 g||1033 g||870 g||470 g||510 g|
|Packed Size||10 x 39 cm||16 x 30 cm||15 x 33 cm||12 x 30 cm||10 x 38 cm|
|Size (Length/Width)||213 x 66 cm||215 x 80 cm||251 x 89 cm||235 x 80 cm||213 x 66 cm|
|Material||3-layer Gore-Tex Respiration||3-layer eVent||3-layer ToddTex||3-layer eVent||2.5-layer Pertex Shield|
|Head Area System||Single-Pole System||Single-Pole System||Free-Standing ( Flexible Wire)||None||Single-Pole System|
1. Outdoor Research Alpine Bivy
The Outdoor Research Alpine bivy sack is very popular among hikers and mountaineers as it provides quite good comfort while being relatively light – it weighs merely 907 grams. The bivy sack is made of a 3-layer Gore-Tex Respiration Positive fabric which offers great tear- and abrasion-resistance. It also provides good weather protection and breathability. Due to the fabric, condensation issues rarely appear in the Outdoor Research Alpine Bivy. The floor is made of resilient nylon for increased durability and water resistance. The bivy sack allows you to suspend the fabric above the head as it comes with a pole. The pole comes in a sleeve outside the bivy sack and can be secured with Velcro closures at the bottom. Additionally, the bivy sack is equipped with sleeping pad straps, five stake loops, internal mesh pocket and no-see-um mesh to keep the insects out. The Outdoor Research Alpine bivy sack is perfect for lightweight hikers who want a reliable shelter for their adventures.
2. Rab Ridge Raider Bivy
Best use: Winter trips
The Rab Ridge Raider bivy sack offers slightly more space (length, width as well as height) than the Outdoor Research Alpine bivy sack. The upper part of the bivy sack is made of a 3-layer 40-denier eVent fabric which is known for its superb breathability and durability while the floor is made of durable abrasion-resistant nylon. The bivy sack comes with one DAC Pressfit pole so that you can suspend the material in the head area. When the head area is suspended the bivy sack offers an internal height of 58 centimeters which is indeed impressive for such a light and small (when packed) shelter. The pole comes in the external sleeve and can be secured with stakes to stay upright. Additionally the bivy sack is equipped with six stake loops and a no-see-um mesh door to keep the insects out. All in all, the Rab Ridge Raider bivy sack is a great option for lightweight hikers and mountaineers who want a shelter that is bigger than an ordinary bivy sack, but smaller and lighter than a one-person tent
3. Black Diamond Big Wall Hooped Bivy
- Emergency shelter
The Black Diamond Big Wall Hooped bivy sack differs from the bivy sacks listed above by being more minimalistic. It features a significantly lower head height than the Outdoor Research Alpine and Rab Ridge Raider as it does not use a pole system to suspend the material. Instead it uses a sewn-in flexible wire that suspends the material automatically when the bivy sack is unpacked. The good thing is that the flexible wire makes the bivy sack easier and faster than to set up than with a pole system. The Black Diamond Big Wall Hooped bivy sack is made of the Todd-Tex waterproof/breathable material. Todd-Tex material is very similar to Gore-Tex: it uses a PTFE membrane that is bonded to the face fabric and internal fabric (3-layer design). The material provides good weather protection as well as decent breathability and thus efficiently minimizes the buildup of condensation. Additionally, the bivy sack is equipped with a dual zipper, no-see-um mesh and taped seams. The Black Diamond Big Wall Hooped bivy sack is best for those who want a minimalistic but very reliable shelter for trips in all conditions.
4. Rab Alpine Bivy
- Emergency shelter
The Rab Alpine is another high-quality minimalistic bivy sack that is best for demanding trips where lightweight and highly reliable equipment is required. The Rab Alpine bivy sack is the lightest and the smallest (packed) product in this review. It is made of the same material as the Rab Ridge Rider bivy sack – a 3-layer eVent material which is highly breathable and offers decent weather protection. The Alpine bivy sack has a durable floor which uses 70-denier nylon for reinforcement. Unlike the other bivy sacks in this review, the Rab Alpine is not equipped with a pole system to suspend the fabric in the head area – it has a completely minimalistic design. However, it is mummy shaped in order to fit technical sleeping bags. Even though it offers very little space, condensation is rarely an issue as the eVent fabric provides great breathability. The Rab Alpine bivy sack is primarily designed for mountaineers and alpinists and offers best performance in winter conditions (snow).
5. Outdoor Research Helium Bivy
- Emergency shelter
The Outdoor Research Helium bivy sack offers similar space and functionality to the Outdoor Research Alpine bivy sack. It has identical dimensions, comes with one Delrin pole to suspend the head area and is equipped with no-see-um mesh to keep the insects out. However, the Outdoor Research Helium bivy sack uses Pertex Shield material instead of Gore-Tex Respiration Positive and is therefore significantly lighter – it weighs merely 510 grams. It also provides good protection against rain and wind. On the other hand the Pertex Shield material does not provide as good breathability as Gore-Tex and thus this bivy sack is more prone to condensation issues. The Outdoor Research Helium bivy sack is best for those who want a minimalistic shelter for hiking in dry weather when the bivy sack doesn’t have to be completely sealed (improved condensation resistance) or those who want an efficient lightweight emergency shelter.
3. The most attractive product in the review