Designs from a life on the road

Trek 3 Sleeping Bag

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Over the  years I have using this Trek 3 Sea to Summit sleeping bag and think it represents great performance at a reasonable cost.

It's not a cheap sleeping bag....but that's the point!
Sea to Summit started as a sleeping bag company and have many years of experience to draw on.

Here is what they say about their Trek 3 series.

The classic tapered rectangular sleeping bag - redefined!
Incorporating our 2D PermaShell™ fabric and a premium 650 loft down, the Trek bags are a refined classic. The 60/40 fill ratio in the Trek bags is maintained using a side block baffle and differential cut shell. In the top of the shell a 3D side wall, a feature normally reserved for technical alpine sleeping bags, provides more space for the down to loft right to the edge of the bag.

An oversized security pocket located inside the bag is easily accessible, ideal for stashing passports and other valuables while travelling. The soft touch lining fabric is down proof (you won't get out of it looking like a snow ...person...) by construction and highly breathable offering a comfortable sleep.

But has a full length side and foot zip allow it to be opened out into a full doona for use indoors and warm weather.

What really impresses me about this bag is the attention to detail. The a storage bag for home and compression storage bag for the road. We are encouraged to register our bag with Sea to Summit for example. The zippers actually work from inside and outside the bag and don't snag due to the clever stiffened baffle system. The Hood drawstring works two way, closes at the head and/or the chin.

I understand that you don't spend close to 400 bucks on a sleeping bag very often and want to be sure you are getting an excellent item. That is why I have put time into checking it out. This is the best sleeping bag I have ever owned!

Length / zip options:
  • Regular - left or right zip - for people to185cm/ 6ft

Please note Regular size right zip bags ordered in for you. Allow a week for despatch.

Season ratings:
  • Spring/Autumn/Winter-lite (fine in almost all Aussie winter conditions)
Trek 3 come in Short as well.  Please email me for availability.


Tapered rectangular- The tapered rectangular design offers a good compromise between the comfort of a generous cut shape and warmth of a closer fit. The tapered rectangular design offers a good compromise between the comfort of a generous cut shape and wa
2D PermaShell™ DWR shell fabric, differential cut shell with 3D side walls
60/40 down fill ratio, 650 Loft 85/15 Premium Duck Down, Fill weight: Short 700 g/25 oz | Regular 700 g/25 oz | Long 750 g/26 oz
Side block baffle, zip draft tube with anti-snag, cushioned internal hood drawcord with dual adjustment,
2 x 2 way YKK #5 non snag zips, side and foot separate zip, opens to doona. Large sized internal security zip pocket
Other stuff to know
Includes lightweight Ultra-Sil® compression bag 15 litre down to 7.8, mesh storage cell
Bag weight: Regular 1220 g/2 lb 11 oz | Long 1310 g/2 lb 14 oz


Fabrics – 2D PermaShell™

2D PermaShell™ fabric used in Trek series bags is a high-density weave, 33 denier Nylon with a DWR finish. This material is highly vapour permeable and down proof by construction therefore it does not rely on coatiings.

Fabrics – Lining 650 Loft Series

The lining material is a high-density weave, 40 denier nylon. This fabric is engineered for comfort using a high filament count to achieve a soft surface and silky hand feel.

Anatomically Tapered Box Foot

The natural position your feet will take when lying flat is relaxed at ease and slightly stretched out. The anatomical cut box foot tapers in three directions. There is vertical taper from the toe to the heal creating a slant that matches the relaxed form of your feet. Along the outer edge of your foot there is a trapezoidal taper that provides a form fit, keeping down close to your extremities so they don’t get frostbite. From the top view, there is an outward taper from the ankles to the feet. This creates room for your toes to have great circulation and traps warmth in the foot box. This design exists in both the Alpine and Traverse bags.


All Sea to Summit sleeping bags use YKK #5 reverse zips, this allows you to un-zip the sleeping bag from top and bottom for temperature regulation.
Trek bags are fitted with a fixed zip length for all sizes. These bags can be zippered together in any combination of model and size.

Anti-Snag Zip System

Neatly hidden in the draft tube is a super high-density 210D poly cloth. This fabric is exceptionally stiff and was originally engineered for use in high performance race sails. The lightweight, durable, stiff finish provides an excellent zipper anti-snag.

Hood Design

Trek series use a 2-Dimensional cut.

These hoods easily pull into a form fitted profile using the dual-adjustment drawcord.

Internal Drawcords

Around the perimeter of the hood an internally constructed drawcord tunnel ensures the cord is buried deep within the down. When drawn closed the hood forms a comfortable seal around your face. A low profile Nifco dual cord adjuster is used for comfort and durability, offering a versatile fit. The hood closure uses a non-stretch cord for refined adjustment, while the neck collar uses an elastic cord to stretch with you as you move in the bag.

Security Pocket

A large Security pocket is located inside the chest area, it can fit a passport and wallet or be used to stow your electronic devices. Anti-snag coupled with a YKK Invisible Zip ensures an ultra low profile for comfort against the skin.

Differential Cut Shell & Lining

Down insulates best when it is uncompressed and fully lofted. To help the down loft correctly, we use a differential cut shell and lining. The top shell of all Sea to Summit sleeping bags is cut larger than the lining. This creates space in between for the down to loft fully. In addition we use 3D side walls which gives the distinctive vertical sides to our sleeping bags, this further aids vertical loft along both sides of the bag. In the bottom of the bag, we use a reverse differential cut. By increasing the size of the lining relative to the shell, down lofts up to fill the voids around your body, torso, legs and the small of your back. Trapping heat close to the skin is essential for efficient warm sleeping.

Offset Baffles

Offset baffle construction provides a stable structure that allows the down to loft to the correct density and minimizes loss of heat through seams. This improves thermal efficiency of the sleeping bag without adding unnecessary weight of complicated baffle construction.

Side Block Baffle & Fill Ratio

The loft is optimised using a side block baffle construction which allows the bags to be filled with a different ratio of down in the top and bottom. We have put more down in the top of the bag where it is most effective as the down isn’t compressed by your body weight. The exact ratio of down fill must be matched to the shape of a sleeping bag. The Micro bags’ slim fit forms a tight cocoon around the body, when you toss and turn at night, the bag rotates with you. For this style of bag it is best to use a 55/45 (top/bottom) fill ratio. In the Trek, Traverse and Alpine bags a 60/40 fill ratio is more suitable. These bags are a generous cut and have room inside to rotate without the bag following.


In a world of technical brilliance it is remarkable that the performance of certain natural products have not been surpassed. Despite advancements in modern fibre technology, down is still the best insulator warmth for weight. Down forms the lightweight undercoating of birds, insulating them in very cold environments. The down we use is a by-product of the duck and goose meat industry. Like most natural products, down quality depends on many variables; predominantly the species, the feather content and the age. The best quality down is sourced from older birds, consisting of large plumes and clusters that create hundreds of thousands of tiny pockets, trapping body heat to provide unmatched insulation.

Not only does down have the best warmth to weight ratio, it is also the most durable sleeping bag insulation. If kept dry and occasionally washed using the recommended method, it will last a lifetime.


Loft is a measure of volume for a given weight of down. It is used to describe the quality of down, relating directly to the insulating performance. High loft down is warmer for a given weight than low loft down. Higher lofting down will fill a larger volume of space for a given weight, as a result, less down weight is required to fill each baffle in a sleeping bag. This translates to a lighter sleeping bag. The most common measure of loft is called Fill Power. 650 Fill Power implies that one ounce of this down will loft to fill a volume of 650 cubic inches. 850 Fill Power implies that one ounce of this down will loft to fill a volume of 850 cubic inches.

650 Loft Duck Down

In the Sea to Summit Trek series, our 650 Fill Power duck down is a high quality insulation that sets the benchmark for sleeping bags in its class. All of our 650 Fill Power down is tested in accordance to the IDFB standard.

Using the pack - store - wash system supplied with all Sea to Summit sleeping bags, you will ensure maximum loft from your bag.

To help you care for your sleeping bag and store it properly, all Sea to Summit sleeping bags are supplied with three storage sacks.

1.A Sea to Summit Ultra-Sil® compression sack for easy packing

2.An oversized mesh storage cell to ensure the down maintains optimal loft during long periods of storage

3.A large cotton sack to protect your bag when laundering

Use the Sea to Summit Ultra-Sil® compression sack to pack and compress your sleeping bag for an expedition. Stuff your sleeping bag in from the foot first, tighten the drawcord and gently compress the stuff sack. To ensure the best performance from your sleeping bag, do not store under compression for long periods.

The mesh storage cell has been specifically designed to store your sleeping bag in between trips. Air out your sleeping bag thoroughly before storing and do not store damp. Store in a clean dry place. This storage cell will help maintain the loft of your sleeping bag.

The cotton laundry sack has your sleeping bag washing instructions printed on it. We recommend hand washing, if you use a washing machine, use only a front loading machine. Sea to Summit recommends the use of Granger’s™ down wash or similar. Use the laundry sack to protect your sleeping bag when tumble drying. Caution: use low heat/delicates setting only.

With the correct use of these three supplied storage sacks you can expect many years of warm cosy nights in your Sea to Summit sleeping bag.

Temperature Rating

EN13537 is a European standard for sleeping bag temperature ratings.

Everyone sleeps differently; some people are very warm sleepers while others feel the cold easily. There are many factors that affect your warmth and comfort in a sleeping bag. An important factor is that you use a good insulating mat, so your body heat isn’t drawn into the cold ground you are sleeping on. Other factors include your tent or shelter, gender and metabolism, clothing, sleeping bag liner, use of the hood and your daily calorie intake.

Although the EN13537 standard does not identify a single precise temperature a tested sleeping bag is suitable for, it does provide an industry standardised temperature range that a typical user can refer to as a guide for the conditions their bag will be most comfortable in.

The EN13537 standard provides three temperature levels to guide a consumer in their choice.

Comfort - the temperature at which a standard woman can expect to sleep comfortably in a relaxed position. If you consider yourself a cold sleeper use this rating to decide the coldest temperature the sleeping bag is suitable for.

Lower Limit - the temperature at which a standard man can sleep for eight hours in a curled position without waking. If you consider yourself a warm sleeper you can use this rating to decide the coldest temperature the sleeping bag is suitable for.

Extreme -
this is a survival only rating for a standard woman. Between the lower limit and the extreme rating a strong sensation of cold has to be expected and there is a risk of health damage due to hypothermia. This is an extreme survival rating only, We do not recommend you rely on this rating for general use.

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