Guide to Fourth Element Drysuit Undersuits

Guide to Fourth Element Drysuit Undersuits

A little bit of history and theory

At the open water course, every scuba diver learns that the human body loses heat 25 times faster in contact with water than air. There are also a few factors affecting our thermal comfort underwater: 

  • Conduction - transfer energy from one particle to another - we lose heat in contact with water.
  • Convection - the warmer elements of a medium are less dense than others; therefore, movement occurs, replacing warmer elements with cooler
  • The physiological response to cold stress is to reduce blood flow to extremities.
  • Physical effort during diving affects heat loss.

People have been taking a plunge into the blue waters since ancient times. Initially, for fun and foraging, but soon after discovering underwater treasures, salvage professional and commercial diving was born, with the need to stay deeper for longer. Commercial divers in classic suits used a selection of diving undergarments made from natural fabric. My grandfather - a maritime engineer, working on underwater projects at the end of the 1940s and early 1950s, used woollen leggings and tops with core silk elements for extra warmth. A lot has changed with the invention of synthetic materials, and soon after, they were successfully employed in aeronautics and commercial diving. When I started scuba diving in 1990s, commercial-grade diving undersuits for scuba divers were still very expensive for recreational divers, so we were looking for alternatives. I remember my first diving undersuit - a second-hand post soviet army helicopter pilot's suit. They were made of a mixture of natural and synthetic materials with some excellent insulation properties, enabling us to dive cold waters of the Baltic Sea. Unfortunately, they had a significant flaw for scuba diving - they were too bulky and buoyant to use, resulting in additional ballast needed for a dive - by all means, they were not a perfect solution.

Thanks to diving pioneers and divers themselves, one of the most successful lines of products are designed by divers for divers. The best products often come from a sport's true passion, and that's the case with the Fourth Element range of drysuit undersuits. "In 1999 after a dive in Sharm-el-Sheikh, Jim Standing and Paul Strike chewed the fat over a post-dive bevvy. Their vision was to design better thermal clothing to get more enjoyment from cold water diving. "Equipment For Adventure" became their slogan, and as time passed, they chose to put the ocean at the heart of their business. As well as stylish, durable and warm clothing, Fourth Element now engineer the latest fabric technology". (Cath Bates Blog "Fourth Element - A Brief History").


What is the best drysuit undersuit for scuba diving:

  • moisture wicking
  • lightweight, low bulk, and low buoyancy
  • retaining insulation properties even when wet

Assess your needs and conditions.

A good drysuit such as Fourth Element Argonaut is our first line of protection underwater. But your dive will be only as good as the thermal layers you choose to wear on your dive. There is nothing worse than feeling cold on the dive - your hands getting cold, your breathing speeds up, and very often, a dreaded urge to pee emerges, adding to the stressing factor underwater. The easy solution is to wear a suitable drysuit undersuit for your diving mission. The ultimate comfort underwater is an outcome of employing a correct set of layers. 

Your drysuit undersuit choice should be determined by the following:

  • Length of your dive?
  • Water temperature? 
  • Level of exertion expected during a dive?
  • Type of drysuit you wear (neoprene drysuits will require a thinner undersuit)

Level 1 - Fourth Element J2 - Drysuit Undersuit Baselayer

A fast-wicking base layer is the key. It takes water away from your body. One of the best products for diving undersuits I have ever used in scuba diving is the Fourth Element J2 Baselayer. I have used this garment with other fourth element undersuits to the best effect. This particular undergarment has been developed explicitly for the Mexico epic international cave exploration project in Sistema Cheves. Cave explorers stayed underground for weeks - eating, sleeping, scuba diving and climbing to push the limits of exploration in one of the most extensive cave systems on the planet. The J2 baselayer for dry suit undersuits offers knit in a special grid pattern maximising air retention close to your skin and wicking moisture away to keep the skin as dry as possible. Moreover, it contains silver ion impregnated fibres offering anti-bacterial properties. 

Fourth Element J2 Baselayer Undersuit

Fourth Element J2 undersuit features: 
  • Developed for J2 caving expedition
  • Tested for 19 days, 24 hours a day
  • Anti-microbial silver ion technology
  • Lightweight and compact
  • Fast-wicking extreme performance
  • Perfect for extended drysuit diving

Level 2 - Fourth Element Xerotherm - Medium Drysuit Undersuit

The Fourth Element Xerotherm Set is the ultimate base layer system and is perfect for divers wearing neoprene drysuits like the Fourth Element Hydra that require a thinner thermal layer to control moisture and a comfortable layer against the skin or wear it beneath a thicker thermal layer such as the Fourth Element Arctic range for trilaminate drysuitsThe Xerotherm fabric is incredibly stretchy, making it very comfortable to wear. The way the material has been knitted gives it one of the highest wicking speeds of all diving undersuits, drawing moisture away from the skin quickly to help maintain your body temperature.

Fourth Element Xerotherm Undersuit


Fourth Element Xerotherm Undersuit features: 
  • Outstanding thermal performance
  • Lightweight
  • Low bulk and buoyancy
  • Extremely fast wicking
  • Hardwearing
  • Machine washable
  • Performs when wet


Level 3 - Fourth Element Arctic - Heavy Drysuit Undersuit

The Fourth Element Arctic Undersuit Set is a fantastic value for money, a complete package that comes with the arctic top and leggings. The Arctic undersuits use two layers of high-efficiency insulation to help keep you warm. The fabric is fast wicking to draw moisture away from the skin and even continues to insulate when wet. The Fourth Element initially designed it to be used under a neoprene drysuit such as Hydra. Still, eventually, it became hugely popular with trilaminate drysuit users and was employed in combination with the J2 baselayer.

Fourth Element Arctic Undersuit

Fourth Element Arctic Undersuit Features:

  • Dual-layer construction
  • Low bulk, high insulation fabric
  • Performs even when wet
  • Upper right arm zipped pocket
  • Thumb loops
  • Ankle loops


Level 4 - Fourth Element Halo AR Drysuit Undersuit

The new Fourth Element HALO AR Undersuit is a worthy replacement for the successful HALO 3D Undersuit. It has been updated with a new design, extra features and material almost out of this planet. The new Halo AR, just like its predecessor, is the warmest undergarment in the Fourth Element range of dry suit undersuits. The new wetsuit is lower in bulk and buoyancy but provides as much or more thermal protection. This exceptional undersuit will appeal to beginners, advanced and technical divers who enjoy diving in cold and temperate waters all year round. It will also work well together with Fourth Element J2 Base Layer.

Fourth Element Halo AR Undersuit

Fourth Element Halo AR Undersuit Features:

  • Specifically anatomically designed for men or women
  • A°RGON™ -Extreme performance thermal insulation invented for extreme environments
  • Body-mapped Thermal Protection in most critical areas
  • High-performance material with low bulk
  • Design optimised for horizontal trim
  • Design allowing multiple positions for P-valve hose
  • Includes materials used in outer space for ultimate warmth
  • The waterproof and windproof outer layer
  • All-way stretchy internal fleece for a snug, comfortable fit
  • Works exceptionally well with Fourth Element Baselayer
  • Machine washable
  • Outer: 44% Nylon / 50% Polyester / 6% Elastane Inner: 95% Polyester (74% recycled) / 5% Elastane / A°RGON™ Insulation
Fourth Element Drysuit Undersuit Collection

Shop Fourth Element Undersuits!

Lastly, we want to know your diving experience and thoughts on owning your drysuit undersuits. If you have any questions, we are always a few strikes of the keyboard or a phone call away. Please send us an e-mail at or call on 020 8994 6006.