In fact, when we slept in it in -13 degrees C, we had on baselayers, a jumper, a down jacket, thick socks, a hat and gloves. I’ve always been impressed by its performance, be that on a rainy thru-hike of Germany’s Black Forest National Park, dozens of winter nights in and around Snowdonia’s Glyderau, or 10 chilly October nights in Wyoming’s Grand Teton National Park.

If you went for a Rab Ascent 900 (or any 4 season bag) for the cold, you’ll hate it in the warmer months and also be lugging around unnecessary weight. They tested the bag according to EN13537 (which is an industry standard means of testing how warm sleeping bags are), and having used the bag for over three years, we definitely have some thoughts on these numbers (which we cover below).I never had to tighten the neck baffle, because it's large and wraps around my neck nicely and have had the hood loosely fitted around my head and was warm. Though overkill, you can also use it as a blanket in the summer if you poke a leg out of the side, and the durable outer material is protective and comfortable to sleep in. If you use the provided stuff sack, you can get it down to the size of a watermelon or a standard football, and weighing just over 1. We’ve slept in it in all weather on Dartmoor National Park (including a super chilly deep winter camp where the mercury without wind chill hit -13 degrees Celsius), and we even used it at the height of the summer on a large meet up when all other bags were taken.

Initially, we were quite worried about this, wondering how long it would take until the bag was void of insulation altogether. It comes with a host of premium features like insulated baffles and ultra-comfort lining for a great night’s sleep.

I think we are looking at duck down and goose down being on opposite ends of a warmth/cost spectrum. I've been doing my usual procrastinating at work and have been looking at deals on 4 season sleeping bags.

Very light, good product, but it broke when I used the zipper for the first time, which made me unable to close the quilt all night. As mentioned, we bought it back at the end of summer 2020 and have used it innumerable times over the years. Additionally, the zipper along the side of the bag is strong, thick and easy to open and shut, and when operated from inside the bag it rarely snags. Presumably, this is down to the soft and thin inner that — despite being a joy to sleep in (and helps keep the weight of the sleeping bag down) — the duck feathers can easily penetrate when you roll around overnight. Im currently in the market for a new sleeping bag as my current one (Ray Mears Woodlore 4 season) is too heavy and bulky for anything more than a 2 day hike and camp.

A common trick for making sleeping bags more malleable, this allows you to almost vacuum-pack the sleeping bag by pressing out all of the air inside it.

I am always cold yet this bag kept me toasty warm on my recent trip to Stok Kangri, I camped at 5000m and was very warm every night with no additional liner needed. Featuring a thick baffle along the length of the side zip, as well as a huge baffle and lofty hood around the top of the bag, it’s built to keep you warm in colder climates – and in my experience, it does just that. My advice would be to get a Rab Ascent 500 or possibly 300 for spring/summer/autumn and supplement it with a cheap summer bag for winter. As one of our expert campers, Craig revels in testing camping equipment and knows a sturdy shelter from on that will give up the ghost when conditions become challenging. In general, then, fill power is a useful marker for understanding how much down you might need to achieve the same insulatory effect.

Packs small so fits into 85ltr rucksack bottom sleeping bag compartment, large extra storage bag is good. I had to wear all the clothes I had in my pack and wrap what was left of the defective sleeping bag around me as best I could. We’d bet that you’d see the Leviathan’s unmistakable off-yellow hue emanating from at least a quarter of them. However I can't find much online about it, has anyone got or owned one before and can give their thoughts on it? Ive used it this November in Scotland where temperatures just dipped below freezing and it was fine, just about.