Sea To Summit Traverse XTII sleeping bag

By Used by Australian Geographic Adventure Editor Justin Walker 28 March 2014
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This feature-packed sleeping bag keeps you comfortable in a range of temperatures.

The Annapurna-Dhaulagiri Circuit, Mt Kenya, Canada’s Chilkoot Trail, The Franklin River. In the past eight months, this Sea To Summit (STS) Traverse XTII sleeping bag has been tested on all of these adventures.

The bag, one of STS’s Traverse range, is feature-packed: a relaxed mummy shape; snug 850+ Loft European goose down, differential-cut shell and lining (the top of the bag’s shell is cut larger than the lining to add extra space so the loft can “fluff up” fully); side walls (again, to aid lofting); offset baffles, two-way YKK zips (side and foot) and, uniquely, STS’s patent-pending 3D NanoShell technology.

Yep, it is a mouthful, but the 3D NanoShell tech is this bag’s distinguishing feature and describes, according to STS, “a condensation management system that insulates, repels water and protects loft”.

This translates to a combination of a 20-denier NanoShell face fabric that is water-resistant (DWR-treated) and breathable, covering a non-woven, silicon-encapsulated layer underneath, that in turn protects the down, which itself is contained on the inside by a 20-denier polyester lining.

The technology is designed to transfer moisture – in the form of perspiration –outside the bag, while maintaining wind/water-resistance to the occupant, along with ensuring the down fill does not get wet/damp.

During the past eight months, I’ve used the XTII in temperatures ranging from 30°C-plus down to -10°C. The only time it didn’t provide a warm sleep was during the ascent of Mt Kenya where, at High Camp, the below-zero temps – and a too-fine bag liner – meant I experienced a slightly uncomfortable night.

The XTII’s comfort rating is -5°C but that will always depend on numerous factors, such as occupant body heat.

Due to their design, mummy-shaped bags are often constrictive, but the XTII’s generous upper section, with its wide shoulder/mid-body was perfect for this tester, as it offers ample room to roll over. This extra room hasn’t come at the expense of too much extra ballast, either – the regular bag weighs 1210g – and it compresses very well.

The bottom section’s foot-zip allows for additional temperature control and also allows you to open the bag right up to use as a doona-style cover, over your bag liner. On more humid mornings I woke up with a slightly damp outer but it had no effect on the down’s warming capabilities – and the inner was moisture free.

The Traverse XTII’s big appeal is the effective use of new technology, combined with its versatility (you could use it across all seasons, with the only caveat being not for extreme cold regions; STS has an Alpine range for that).

For the asking price (which includes a compression bag, storage bag and washing bag), you get a sleeping bag that is innovative and very effective.

RRP $699.95