Bivy Sacks 101: What You Need to Know

Bivy Sacks: An alpine hiker in the snow lying in her bivy sack

In this post, we'll take a look at:

Ever heard of bivy sacks? They’re a secret weapon for those who want to reduce their gear weight without giving up protection from the elements.

In this post, we’ll cover all you need to know about bivy sacks. Whether you’re a curious explorer or a seasoned adventurer, you’re in the right place.

What Exactly is a Bivy Sack?

A bivy sack, which stands for bivouac bag, is a clever piece of outdoor gear that, believe it or not, has been around for centuries but started to gain popularity in the 20th century when soldiers began using them in combat. Essentially, it’s like a lightweight, waterproof cocoon for your sleeping bag.

The term ‘bivouac’ means to camp without a traditional tent or shelter, and that’s precisely what bivy sacks allow you to do. They’re designed for those who want to travel light and don’t mind embracing the open air. On average, an ultralight bivy sack is 30-40% lighter than an ultralight 1-person tent.

However, bivy sacks are not just for extreme mountaineering adventures; many outdoor enthusiasts use them as their primary shelter. If you choose to go this route, remember that they only add about 9 to 18 degrees Fahrenheit of insulation. So, consider using a warmer sleeping bag if needed.

Bivy Sack – Pros

Bivy Sacks: An ultralight backpacker enjoying his morning in his bivy sack in scenic mountains

There are several compelling advantages to using a bivy sack:

  1. Lightweight and Compact: Bivy sacks are incredibly light and pack down to a fraction of the size of a traditional tent. If you’re keen on reducing the weight of your backpack and having more space for essentials, opt for a bivy sack.
  2. Weather Protection: These sacks offer dryness and shield you from the elements. Whether it’s rain or a mountain chill, a bivy sack creates a protective cocoon for you, your sleeping bag, and gear.
  3. Warmth: Bivy sacks can add 9 to 18 degrees Fahrenheit of warmth to your sleep system. They trap heat effectively, making chilly nights more comfortable. This added warmth can be a game-changer when camping in colder environments.
  4. Minimalist Camping: Bivy sacks enable camp setup in tight or rocky areas, overcoming tent-pitching challenges. They expand your overnight options, from rock ledges to snowy caves.
  5. Quick and Effortless Setup: No need to spend time pitching a tent; bivy sacks are ready in seconds. After a long day, you can quickly slip into your bivy sack and focus on what matters most: resting up for the next day’s journey.

Bivy Sack – Cons

Like any outdoor gear, bivy sacks come with their own set of disadvantages. Understanding these is crucial before deciding if a bivy sack is right for you.

  1. Privacy: Bivy sacks provide limited space and privacy, making tasks like dressing challenging, which may not suit those who prioritize personal space.
  2. Condensation: Condensation can be an issue inside bivy sacks, particularly in humid conditions. It’s essential to manage airflow to minimize this problem.
  3. Usage Challenges: Getting in and out of a bivy sack can be tricky, especially if you’re not used to it. It may take some practice to master.
  4. Wet Weather Challenges: In heavy rain, setting up a bivy sack and transferring gear can be challenging. Wet gear and clothing can make for a bad experience.
  5. Claustrophobic Feel: Some individuals may find the confined space of a bivy sack uncomfortable, especially when fully zipped up.

TLDR: Bivy sacks are ultralight and enable you to sleep in tight spots where larger shelters won’t fit. Nonetheless, having a well-defined strategy to deal with condensation and wet weather is essential.

Also consider checking out our post comparing a bivy sack to a 1-person tent.

Mastering Your Bivy Sack: Tips for Use

Bivy Sacks: An ultralight backpacker enjoying her morning meal next to her bivy sack in a gorgeous coastal national park

Let’s explore some usage tips to maximize your experience with this minimalist shelter.

Tips to stay warm during the night:

  1. Pack Strategically: When using a bivy sack, consider how you pack your gear. Place essential items like your sleeping mat, sleeping bag, and any items you need for warmth at the foot of your sleeping bag. This arrangement ensures quick access and keeps your essentials within reach.
  2. Use a Buff or Balaclava: Consider bringing a lightweight buff or balaclava to cover your face during chilly nights. This extra layer can add comfort and warmth to your sleeping experience.
  3. Additional Insulation: In cold weather, enhance your comfort by placing an ultralight tarp underneath your bivy sack and using two sleeping pads – a closed-cell pad and an air pad – for better insulation from the ground.

Tips to manage condensation and fight wet weather:

  1. Keep Moisture Out While Cooking: Cook meals away from your sleeping spot on wet nights to keep moisture out of your bivy sack.
  2. Reduce Moisture Buildup During Night: To minimize condensation inside your bivy sack, avoid breathing directly into it. Instead, cinch the sack’s hood around your face while leaving a small gap for airflow.
  3. Protect Your Gear: Since most of your gear will be exposed, consider using a backpack liner or cover to shield it from precipitation and keep it dry.
  4. Air It Out: If conditions allow, flip your bivy sack inside out during the day to prevent moisture buildup, which is particularly helpful in humid areas.
  5. Consider a Water-Resistant Sleeping Bag: Choosing a water-resistant sleeping bag adds an extra layer of protection against moisture and unexpected weather.

These tips will help you get the most from your bivy sack adventure. Don’t worry; they become easier with practice, and you’ll quickly see the benefits of this approach to camping.

Final Thoughts

In conclusion, bivy sacks, or bivouac bags, are a lightweight and minimalist alternative to traditional tents, gaining popularity among outdoor enthusiasts for their portability and weather protection.

They offer benefits like lightweight portability, weather protection, added warmth, and quick setup. However, challenges include limited privacy, potential condensation, and a learning curve for usage.

If you’re still unsure about whether to make the leap into bivy sacks, we recommend checking out Ronald Turnbull’s book, ‘The Book of the Bivvy,’ for a closer look into the world of bivy enthusiasts.

Looking for a bivy? Check out the TOP 5 most ultralight bivys on the planet in our guide.


Is a bivy bag waterproof?

Yes, a bivy bag is designed to be waterproof. These compact shelters are typically constructed with waterproof or water-resistant materials, making them effective at shielding you and your gear from rain, snow, and other moisture in the outdoors. However, it’s essential to note that the level of waterproofing can vary among different bivy bags, so it’s advisable to check the specific product’s specifications and choose one that suits your intended outdoor activities and weather conditions. Proper usage, such as securing the bag’s openings and managing condensation, also plays a role in ensuring its waterproof capabilities.

Should I get a down or synthetic sleeping bag for bivy?

When choosing between a down or synthetic sleeping bag for bivy camping, it depends on your specific needs. Down sleeping bags offer excellent warmth-to-weight ratios, making them great for cold conditions, but they lose insulation when wet. Synthetic bags, on the other hand, are more water-resistant and maintain insulation when damp, making them suitable for wet or humid conditions. Your choice should align with the expected weather conditions and whether you prioritize warmth and weight or moisture resistance.

Spread the word →

Search Insights

Have any questions?

Follow us

More Insights

Suscribe to Our Newsletter

Follow us

hikinglite logo white
©2023 HikingLite - All rights reserved

Start your ultralight journey!

Subscribe now to stay ahead of the pack with the most up-to-date ultralight gear content.