How To Choose The Best Drysuit Undersuits

How To Choose The Best Drysuit Undersuits

How to choose the best drysuit undersuits for your drysuit can be a daunting and confusing undertaking. After all, it could make the difference between a toasty and fun dive, and a freezing uncomfortable one.

But with so much choice out there, how do you know which undersuit is the right one for you? What factors do you need to consider before making your purchase? Even the most experienced of divers are unaware of some of the newer solutions out there to keep them warm while diving, so you’re definitely not alone!

To help you decide which undersuit would suit your needs best, we have put together this blog post, in which we are going to go over the following key areas:



  1. The Basics Of Undersuits
  2. Why Layering Up Works
  3. One Piece vs Two Piece
  4. Core Protection
  5. Performance In Sub-Optimum Conditions
  6. Thermal Socks
  7. Off The Peg or Made To Measure
  8. Temperature Ranges


1. The Basics Of Undersuits

The choice to scuba dive in a drysuit can be made for a number of reasons and for a number of different diving situations. It is true that drysuits are more commonly associated with cold water diving, but that is not their only useful application. Whilst most recreational divers use drysuits for comfort and warmth in the cold, technical divers use them in warm waters as well. They do this to improve your trim, position, and to maintain warmth during decompression stops.

So here you are, with a shiny new drysuit, but that alone won’t keep you warm and comfortable during a dive. As the name suggests, it will keep you dry, but doesn’t have much in terms of insulating qualities. No matter what kind of diving you do, using the right undersuits is therefore vital to ensure you enjoy your dive. You might not quite believe this, but there is actually no dive that you can make in which you can't be kept warm.

Its a statement well worth repeating that a drysuit won't keep you merely will slow your body's cooling. Your underside system can be used to further slow the cooling.

In general, it would be fair to assume that a diver planning a warm water dive will likely be looking to use lightweight wicking layers for their dives. For cold water dives, a diver would probably choose thicker thermal protection and use lots of layers to trap more air. However, the first thing to accept and understand when looking at undersuits is that there is no one best undersuit for drysuit diving. There is no universal solution that works for every diver, as every diver and every dive is different.

First of all, you need to think about water temperature, duration and activity level during the dive. These three factors have the highest impact on diver’s thermal requirements. For instance, diving is quite a lazy sport and most dives do not actually involve that much activity, especially as you become an experienced diver that has mastered essential skills of buoyancy, trim and propulsion. Additionally, your body composition, physical condition and the material of your drysuit will also affect your tolerance to temperature changes. This means that you need to combine any advice you are given with the knowledge of how you personally react to different temperatures.

As such, when you start out investing in drysuit undersuit systems, start by thinking about where the majority of your drysuit diving will take place. Scuba Leeds is based in Leeds, West Yorkshire. Therefore, we dive all year round in the UK. If this is the type of diving you are planning to do, then you would likely be looking to get thermal protection for a range of 4 degrees to 16 degrees. But more about temperatures later.


Why Layering Up Works2. Why Layering Up Works

It may not be what you want to hear, but if you dive in cold water, one of the best things you can do is invest in multiple layers of thermal protection.

Layering up works for all sorts of outdoor activities, and scuba diving is no different. Multiple layers will always keep you warmer than a single thicker layer. This is because warm air is trapped in between each layer, acting as an insulator. With each layer you remove, you reduce the amount of heat trapped, and you will subsequently get colder.

An additional benefit to wearing multiple layers is that you can mix and match layers in order to adapt to the water temperature you are diving in. If you find yourself actually being too warm after a dive for example, simply remove one layer, which will help you stay cooler during the next one. Therefore, this will allow you to tailor your system for the best performance for every condition.

In terms of material, there are also a few things to keep in mind. Your body sweats even when you are relaxed and calm. Therefore, the layer in contact with your skin needs to be able to move moisture away, so it should be made of fast-wicking material. This will prevent you from becoming damp and cold before or during the dive.  Some base layers have been specifically designed to achieve this.

Another thing to bear in mind is that cotton is terrible at wicking moisture, but instead will make you feel wetter and colder. As such, try to avoid wearing a cotton t-shirt as a base layer, as it will prevent your undersuit from doing its job.


3. One Piece vs Two Piece

The first major decision is whether you want a one-piece or two-piece undersuit. Most manufacturers of undersuits offer both solutions. Sadly there is no right or wrong solution, and the reality is that you need to make that call. in certain situations, there are benefits for both. As a general rule, it is down to personal preference.

There are a number of technical reasons why you will choose one or the other, for me, I am way less likely to loose or forget a part of my undersuit combination by selecting a one-piece undersuit. They are easier to put on or take off and are less likely to ride up at the mid-section. Some of them are skin-tight, trapping the heat very effectively. Whilst these do stretch to a certain degree, they are a bit harder to get in and out of, and they may lose elasticity overtimes, which reduces their effectiveness.

Two-piece undergarments are easier to be mixed and matched in terms of style and thickness, and you wear them just as you would wear normal clothes. They serve as great base layers underneath thicker loft-style undergarment suits and allow you to add and remove layers with ease.


4. Core Protection

The areas of your body most prone to heat loss are the head, neck, sides of the chest cavity, and the groin area. The first two are covered by your hood and your drysuit neck seal (see buying a drysuit) - the rest of this area can be described as your core. 

So your undergarments need to be most effective at retaining your body's heat in your core. Some undersuits provide additional thickness in the core, whilst others might provide a more generous fit to allow for layering underneath the core. Some of the modular systems include a sleeveless body warmer/vest option that can be included in your layering options.


5. Performance In Sub-Optimum Conditions

Your undersuit may be used in less than optimum conditions. You won't always only wear a drysuit in cold water with cold surface temperatures. There are many places where whilst the water temperatures remain cold all year - especially if you dive in areas with strong upwellings from deep waters where the diving will be spectacular due to the marine life attracted by the nutrient-rich waters - but the air temperatures can be very hot. In this situation, you may want to consider ease of donning and doffing your clothing so that you only add your undercut just before zipping into your drysuit and getting into the water. 

The other thing you should seriously consider is how your garment performs when wet. Let's be honest - it's only a matter of time before your drysuit leaks - and some of the more modern fabrics will retain their thermal properties even when saturated. Whilst this may be a more expensive option in the initial purchase they may be a worthwhile investment if wearing them means you can continue a dive whilst ‘damp’ where alternative products might mean you have to call a dive due to the danger of getting too cold. 


6. Thermal Socks

Do not overlook this vital component. There are some fantastic thermal dive socks available. Be sure to consider how you will be deploying the socks - will you be wearing a drysuit with boots or do you go for a neoprene sock with rock boots ontop. This is likely to influence the thickness of the sock and therefore the thermal efficiency you need in your product. If using neoprene drysuit socks you will be more likely to require a thinner but high thermal retention material as this will be comfortable under your drysuit.

Remember that whatever you decide with socks, as with all under suits, its important that you allow air to be retired alongside the item of clothing as it is ultimately, the trapped air that provides the insulation. 

With socks - layering can also be used, wearing a thin sock under your thicker specialist thermal product can provide another layer of frapped air. 


7. Off The Peg or Made To Measure

As in all things, made to measure will have significant advantages. Garments made to fit YOU will fit you and provide flexibility in the areas you need movement. However - the downside with this will be the cost - plus a wait whilst the items are made for you. You can also customise the product to match your personal styling - coloured stitching and embroidery are all options that can be available not he made to measure items.

Made to measure will usually be lower cost - so you can perhaps afford to upgrade to a slightly higher specification. Also - sometimes - especially with two-piece items - you can mix and match sizes to get a closer fit.

Ultimately it's up to you. There are few points for style - you should sacrifice looking great on the shore in favour of products that suit your technical needs and provide the appropriate warmth.

Regardless of which of these choices you go for be sure to make certain your suit includes small additional features such as thumb loops and foot straps as there nothing worse than having the suit ride up and leave a calf or forearm uncovered as you wriggle into your drysuit. Don't forget to specify these if you're having a suit made to measure.


8. Temperature Ranges

Unfortunately, because there are so many variables involved there is no hard and fast rule or formula for how to choose the best undersuit as every diver and every dive is different. Things like your physical condition, body composition drysuit materials, and how hard you work during a dive can all affect how tolerant you are to temperature changes. The best advice must always be considered alongside your own knowledge of how you react to different temperatures.

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