Fourth Element Proteus II 5mm Women’s Full Wetsuit

Fourth Element 5mm Proteus II Women's Full Suit – A Serious Thermal Wetsuit for Recreational Divers

The Fourth Element 5mm Proteus II Women's Full Suit is a full-length neoprene wetsuit built specifically for scuba diving, aimed at recreational divers who want serious warmth without sacrificing mobility.

If you regularly dive in temperate water, push your bottom times, or simply run cold, this suit is worth a close look.

What Makes the Neoprene Different

The Proteus II is built from limestone-based neoprene with Eco Carbon Black, which incorporates recycled rubber from scrap tyres into the raw material.

That matters for two reasons. First, the manufacturing process cuts CO2 emissions by 200g per suit compared to conventional neoprene production. Second, Fourth Element uses water-based Aqua-X glues in the lamination and construction, avoiding the solvent-based adhesives that most wetsuit manufacturers still rely on.

If sustainable manufacturing is part of how you choose gear, this is one of the few suits where the eco credentials are built into the material itself, not just the packaging.

How It Keeps You Warm

At 5mm throughout, the Proteus II is rated for water temperatures of 19°C and above. That puts it comfortably in the range for temperate recreational diving, covering most of the UK, much of the Mediterranean in shoulder seasons, and similar environments worldwide.

The warmth comes from more than just thickness. Three design details work together:

• Hydrolock inner neck seal sits against your skin at the collar and blocks the main entry point for cold water down the back of the suit.
• Glideskin wrist seals form a close, smooth seal at the cuffs, reducing the flushing that happens every time you move your arms.
• Hexcore linings on the body core add an extra layer of insulation across the torso, where heat loss matters most during a long dive.

Together, these features give the suit a semi-dry quality, meaning water still enters but flushing is significantly reduced compared to a standard wetsuit. You stay warmer because the thin layer of water trapped against your skin stays warm instead of being constantly replaced.

If you need to push into colder water, Fourth Element designed the Proteus II to layer with a Thermocline vest, shorts, and hood. That combination extends the suit's usable range downward without requiring a completely different system.

Seam Construction

The seams are double-glued, blind-stitched, and taped. That three-step process matters for thermal performance and durability.

Blind stitching means the needle never passes all the way through the neoprene, so there are no holes for water to track through the seam itself. Gluing on both sides of the join before stitching locks the panels together. Taping over the finished seam adds a final barrier and protects the stitch from wear.

This is the construction standard you find on quality thermal wetsuits. It is noticeably more durable and watertight than the flatlock seams used on budget suits.

Fit, Entry, and Flexibility

The Proteus II uses a back zipper with a pull tab leash, the traditional entry point for full suits. The leash lets you reach the zip yourself when suiting up solo.

Fourth Element describes the fit as slightly closer than a standard wetsuit, particularly around the seals. That closer cut is deliberate: it is what allows the neck and wrist seals to do their job. If you are between sizes, sizing down slightly is generally the right call with a suit like this, provided you can still breathe comfortably and move your arms freely.

The neoprene compound used here is noted for greater flexibility than conventional neoprene at the same thickness. For a 5mm suit, that matters. Thicker neoprene can restrict your arm movement and make finning feel laboured over a long dive. A more flexible compound reduces that fatigue.

The suit is also noted for less buoyancy than comparable 5mm suits. That means less lead on your belt, which is a practical benefit on every dive.

Who This Suit Is Not For

If you dive primarily in warm tropical water above 25°C, a 5mm full suit will be too warm and too restrictive for comfortable diving. A 3mm suit or a shorty is the better tool for that environment.

If you regularly dive below 15°C, a wetsuit at this thickness, even a well-sealed one, will not keep you warm enough for extended dives without significant layering. A drysuit is the honest answer for cold-water diving.

The Proteus II sits in its sweet spot in the 15°C to 22°C range, where a well-built 5mm wetsuit genuinely outperforms a cheaper option and where the seal system and Hexcore lining earn their place.

Construction at a Glance

The Fourth Element Proteus II is a well-engineered suit for divers who take their thermal comfort seriously and want a wetsuit that performs close to its rated limit rather than well short of it.