Thermal Undersuit Fourth Element Arctic Expedition

Thermal Undersuit Fourth Element Arctic Expedition
Thermal Undersuit Fourth Element Arctic Expedition

BY THE TIME YOU READ THIS the sun could be splitting the skies, and you’re more than likely wearing shorts and a T-shirt and looking for some shade to gain respite from an early summer heatwave.

The last thing you’ll be thinking about is a thick thermal undersuit.

Unless, that is, you froze your bits off under water during the winter months or you have a dive trip planned to colder climes.

If the latter’s the case, Fourth Element has released its latest hi-tec thermal gear, aptly named the Arctic Expedition. I dived with it throughout the late winter.

Biomapped Design

Fourth Element says it has used its extensive expertise, knowledge of performance fabrics and “biomapped design” to create this latest offering in its Expedition series of undersuits.

The Arctic Expedition has been built using strategically placed layers of high-density fleece, windproof and waterproof fabrics to protect those areas of the body that experience the most exposure during a dive.

The biomapping technology maximizes the thermal protection while minimizing the bulk of the garment giving, it says, greater freedom of movement and comfort.

The Undersuit

The pocket is well placed for diagonally zipped drysuits
The pocket is well placed for diagonally zipped drysuits

The Arctic Expedition is available as a one-piece suit or as a separate top and leggings set, and it was the latter that I chose for this test.

The top is made primarily from high-density fleece with extra layers in key exposure areas such as the chest and arms on the top and on the upper portion of the leggings.

The areas around the calves and ankles have a single layer to reduce bulk and allow for thermal socks to be worn.

The chest, shoulders and arms on the top, along with the seat and knees on the leggings, are covered with what appears to be the maker’s own Thermocline waterproof and windproof material.

This offers invaluable moisture protection where it’s most needed, especially when getting rigged on a wet boat-deck or on the beach.

The areas around the wrists are also covered with the waterproof fabric to preserve its thermal properties when your wrist-seal inevitably lets water through via your carpal tendon groove.

Elasticated thumb-loops fitted on the cuffs aid in getting the arms into a drysuit without the sleeves riding up to your elbows, and cleverly retract when your thumbs are removed so that the loops don’t get caught in the wrist-seals.

A single fleece-lined zipped hip pocket is placed where it can be best accessed when wearing a front diagonal-zip drysuit, and is great for keeping keys safe.

Two hand-warmer pockets are provided on the leggings, along with a pre-cut hole for pee-valve tubing. The waist is elasticated, with a pull cord to hold it in position.

A soft, short, raised crew-neck collar made from soft polar fleece is designed to keep within the confines of the drysuit neck-seal, and the outer main panels are treated with a ceramic print to minimise the effects of abrasion from the inner surfaces of a drysuit.

The leggings have built-in foot-stirrups, so they won’t ride up when donning a drysuit or when diving.

The whole suit is finished in black with contrasting flat-stitched seams and discreet silver and orange screen-printed livery.

The Arctic Expedition is available in men’s and ladies’ two-pieces or a men’s one-piece.

Under Water

At first glance the Arctic Expedition seemed a little bulky, because the thick fleece used in its construction is substantial.

I slid my tight-fitting trilaminate drysuit over it and expected to feel as if I’d been put into a strait-jacket, but was pleasantly surprised to find that the undersuit felt less bulky than it looked and did not restrict any movement. In fact it felt like a much thinner garment.

The insulating properties were immense, keeping my whole body warm for long dives at inland sites where the water temperatures ranged between 5° and 7°C.

On the surface between dives, where severe wind-chill should have been a factor, the Arctic Expedition lived up to its name and continued to keep me toasty-warm.

It is never pleasant to have cold sweat dropping your body temperature during or after a dive or two, always an annoyance with my own thermal undersuits.

The Arctic fleece wicked away the moisture from my skin and left a damp outer shell after a few hours of underwater exertion, but to my delight the inner surfaces next to my skin remained dry.

After use I put the suit through a 30° washing-machine cycle and hung it up to dry. It came out looking like new and smelling fresh, ready for its next outing.


Fourth Element has carved out an enviable reputation for producing garments made from hi-tec fabrics that meet the exacting demands of serious expedition divers and explorers.

The Arctic Expedition is an example of its expertise in this field, and even if you’re not going to the frigid polar regions to get under the ice and study micro-plankton this undersuit system is still worth considering for all your UK winter and spring diving.

I found it to be a supremely comfortable and extremely warm, well thought-out and executed product, one that not only performs exceptionally well but looks great too.

PRICE: One-piece Men’s suit £279. Ladies or Men’s two-piece £279.
SIZES: Men’s S-XXXL and Ladies 6/8-20/22, standard or short leg length.
EXTRAS: Free DrySack
CONTACT: Fourth element website
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