Zero Degree Sleeping Bags

Sleeping Bags For Extreme ExplorersBuilt to Take On Harsh Conditions

Conquer extreme cold with confidence using Sea to Summit's zero-degree sleeping bags. Designed for adventurers who venture into the harshest conditions, our zero-degree sleeping bags offer unparalleled warmth and protection. Whether you're mountaineering, winter camping, or embarking on a really cold expedition, Sea to Summit's zero-degree sleeping bags provide the ultimate defense against the elements, ensuring you stay warm and comfortable no matter how low the temperature drops.

From the robust and reliable Alpine series, designed for high-altitude expeditions, to the versatile and durable Ascent series, which offers a perfect blend of warmth and adaptability, Sea to Summit has a zero-degree sleeping bag to meet the demands of any cold-weather adventure. Each bag is crafted with durable, weather-resistant materials and thoughtful design features to provide superior comfort and protection in the harshest conditions.

Frequently Asked questions

How warm is a zero-degree sleeping bag?

Used with an adequate sleeping pad (a tested R-Value of 5+), with the sleeper wearing heavyweight base layers and an insulating cap, a male sleeper in a ‘zero degree’ bag should be comfortable to around 0°F / -18°C (a female sleeper to around 10°F / -12°C). However - not all bags are tested, and the test may not reveal limitations of a bag’s construction.

Are zero-degree sleeping bags heavier than other warm-weather bags?

A ‘zero degree’ bag refers to a sleeping bag intended for use down to 0°F / -18°C. This requires a lot of insulation (and – if realistically rated – complex construction). The bag weight will be perhaps 2lb / 900g above that of a warm weather bag. Carrying a ‘zero degree’ bag in warm weather is like using the proverbial sledgehammer to crack a nut.

What makes a zero-degree sleeping bag so much warmer?

A bag which will truly keep a sleeper warm at around 0°F / -18°C needs a lot of insulation – which equals a lot of weight. It also needs complex construction in the hood, draft collars and draft tubes (not all bags advertised as ‘zero degree’ bags have these). There are a lot of factors (including an effective sleeping pad) needed to keep warm at these temperatures.

Zero Degree Sleeping Bags

Spark Down Sleeping Bag (-18°C - 7°C)

Trek Down Sleeping Bag (-18°C - -1°C)

Alpine Down Sleeping Bag (-29°C)