Outdoor gear review

Sea to Summit Traverse XTII sleeping bag.


Basic Description:


A great 3+ season bag for backcountry hunts where warmth is key and weight and space in your pack is a high priority.  It has a generous foot box with a separate zippered foot box.  It is filled with 850+ goose down and has the patented 3D NanoShell® which features 3D side walls, offset baffles and it sheds water like a duck! EN tested to 12 degrees and they have another model that is EN tested to 19 degrees.


Just the Facts:


-850+ European Goose Down

-19 oz fill weight and total weight of 2lbs 11oz

-3/4 length main zipper with anti snap stiffener and separate foot box zipper

-EN rated down to 12 degrees

-Compresses from 15L to 5L

-Relaxed mummy shape foot box with larger hood, broader shoulders and larger cut chest





I received this bag from Sea to Summit to test out and review and currently is the best bag I have used to date. You can tell that Sea to Summit really thought everything through and left nothing out on the design of this bag.  I am going to try my best to explain the technical features of this bag.  I will start with the 3D NanoShell®, Most down bags are made up of an outer layer that is treated with DWR to repel water and block wind, this helps to keep the down dry and if you are familiar with the properties of down it is useless if it gets wet. So these barriers are crucial in a bag.  But moisture can come from the inside of your bag by way or perspiration. Sometimes over a weeklong trip it can have a hard time getting all of your sweat out of the bag and passing through the outer shell. So it for condensation on the inside of the outer shell thus getting some of the down wet and over a trip the bags rating can drop a little bit. Sea to Summit introduced their 3D barrier which is in between the outer shell and the down. It allows perspiration to pass through it and keeps the condensation from forming up against the down and getting it wet.  This allows more time for the condensation to make its way through the bag. Very technical and very well thought out, and it is crucial on a backcountry hunt to keep a down bag dry and Sea to Summit helps to make it a little easier.


The construction of this bag is also very well thought out and aids in comfort in the backcountry.  They have their 3D side walls which is a fancy way of saying how they sew the sleeping bag, to form a “box” so it is a roomier more comfortable bag. Most bags just have the top and the bottom sewn together, but this actually has sides which give it more volume and room. The cut of this bag is better than most other bags. It also has offset baffles which help to reduce cold spots and it has a 60/40 fill ratio, meaning 60% of the down is on the top of the bag and 40% of the down is on the bottom. This helps to keep you warmer for the weight of down put in the bag; most of the down on the bottom of you gets compressed anyways and is useless. Hence the reason you need a warm sleeping pad when the temperatures drop.


The features on this bag are all features I love in a bag and will have a hard time using a sleeping bag that doesn’t have them.  The zipper on this bag is better than any zippers I have used due to the stiffener built into the draft tube.  The hood is very well cut and has two very easy to use draw cords and synchs up quite nicely and really keeps out the drafts. The bag comes with a storage sack and a sil nylon compression bag. Which are both nice features, but I would never keep the sleeping bag in the storage bag mine came in because the bag could not fully loft while in the bag. If they had a bigger storage bag I may consider using it, but I like to hang my down sleeping bags in a closet anyways. The compression bag is nice but it isn’t waterproof and I use a dry bag to keep the sleeping bag from getting wet. After all it rains every once in awhile here in the northwest.


This bag’s msrp is $550 but I could find it for as low as $420 online. Either way this is an expensive bag but one I would recommend for the backcountry hunter wanting a high quality bag with a lot of nice features.


What they could do better:


Those features that I have mentioned above come with a little price for you ounce counters however. This is being really picky but if you are looking for a 10-15 degree sleeping bag there are options out there that weigh less.  Now will they have the water shedding capabilities, roominess, and separate foot box zipper of this bag? Well no and that is why they weigh less. So it isn’t really something they could do better just a preference that you need to decide what is better for you and is it worth it?  It would really be nice if they could get this bag under 2.5lbs and keep the same EN rating, then I would really be excited!  But all in all this bag is one of the best bags around and they have a few models with different ratings to choose from and the Traverse XTI which is rated at 19 degrees weighs 2 lbs 6 oz.  I would highly recommend you take a look at these bags if you are in the market for a high end down sleeping bag.


Sea to Summit Traverse XTII sleeping bag.
  • Functionality
  • Value
  • Ergonomics
  • Durability