Exposure Suits

Exposure Suits

JoJo Southgate ·

One of the most popular questions we get asked by our students is ‘What wetsuit should I buy?’ Then we end up asking them lots of questions!
How often are you planning on diving?
Where will you be diving?
Do you feel the cold easily?
etc etc etc
Owning an exposure suit is all down to your individual needs.

What is an exposure suit?
An exposure suit is what you wear while diving – a wetsuit or dry suit! For us UK divers, even if it’s nice, hot and sunny in the Summer you’ll want to be diving in a dry suit all year round. When I started diving, I’d never even heard of a dry suit and I spent £100+ on a 5mm wetsuit that I was told would be fine for UK diving – turned out it wasn’t! Especially after 2 dives at an inland diving lake on an overcast day in September. What you wear in the UK will dramatically differ from what you wear on holiday. I found it quite comical when I went diving in The Keys when I was in a shorty and got told by the guides that I’d get cold very easily – it was about 28°C in the water and they were in dry suits! I was very comfortable in the water and it was lovely and warm, compared to my usual 12-14°C! They were amazed, I was amused.
You’ll find that UK divers favor dry suits all year round and swap them for wetsuits for a nice blue water holiday – unless they are diving deep or in cold water. I’ve yet to take a dry suit on holiday!

What’s the difference?
Both wetsuits and dry suits are used for thermal insulation. A wetsuit will keep you wet and a drysuit keeps you dry! Not rocket science eh…? Let me explain a bit more of each to you…


These are made of a rubber called Neoprene. Neoprene has small cells within it that trap air which provides insulation against the skin. The thicker the suit the more air there is trapped making the wearer warmer. The suits also trap a layer of water between the neoprene and your skin – hence why it’s called a wetsuit as it keeps you wet. Body heat warms the layer of water and helps keep you warm. The suit must be kept tight against your skin with no baggy areas or any bunching up. If your suit isn’t tight enough water will flush through the area between the suit and skin which makes it less effective in keeping you warm. Keeping your core temperature right is important in order to prevent hypothermia. The fit is very important when purchasing a wetsuit, so make sure you get the right one – it’s always worth referring to a manufacturer's measurement chart and try it on before you buy.

There are a variety of suits available – different lengths and a variety of thicknesses. What you choose will all come down to your diving plans. Each of these features will affect when and where you dive. For example, a 3mm shorty may be used in hot, tropical waters by a holidaymaker but they wouldn’t consider wearing the same item in cooler winter waters.

Different Lengths:

  • Full/Long Wetsuit
    These cover the entire body and are available in different thicknesses to suit different water temperatures. Good for cooler waters.
  • Shorty Wetsuit
    These are primarily worn in warmer waters and are still available in different thicknesses. They cover the core body and have shorter legs and arms. Good for warmer waters.
  • Long John/Jane Wetsuit
    These are the same as a full length but without arms.
  • Rashguards
    A thin top (short or long) that tends to be worn under a wetsuit to prevent irritation.


Generally, for Scuba Diving suits, there are 3 thicknesses of suits available: 3mm, 5mm, 7mm. The thinner the neoprene the less warmth there will be, but more flexibility and vice versa for the thicker suits. You may think that a thicker suit would be better all-round to make sure that you are warm but there are some disadvantages to this such as a decrease in mobility and added weight and buoyancy bear in mind that the limbs will work harder for movement against a thicker material which has the potential of wearing you out quicker.
As a rough guide we would advise the below, but don’t forget everyone is different:

  • 25°C and higher - Shorty
  • 20°C - 27°C – 3mm Long
  • 16°C - 21°C – 5mm Long
  • 14°C and lower – 7mm or dry suit

Semi-Dry Wetsuit

These are very similar to wetsuits but provide much better seals on the wrists, ankles and neck. These seals limit the amount of water that enters the area between the neoprene and wearer. You still get wet in these suits but the water that gets trapped does not leave the suit. This means you will be able to stay warm for longer. They are generally used in water temperatures of 10°C - 20°C. They are made of high-quality neoprene; they generally have 2 layers of neoprene which trap water much better. They come in the same 3 different thicknesses as a wetsuit but only available in a full-length option.

Dry Suit

A dry suit in considerably more expensive than a wetsuit – but with good reason! As you may have guessed already, these products are designed to keep you dry. The dry suits work by trapping a layer of air next to your skin, which will essentially keep you warmer as air is a better insulator of heat than water is. To allow the air in your suit you will have a hose that connects to a valve on your dry suit from your air supply, you will have another valve that allows you to remove any access air. You can purchase 2 different types of suit – a neoprene or a trilaminate – and they can come in off the peg sizes or custom made/made to measure. You will also find that you’ll need to wear a base layer/undersuit under the suit, more on this later.

Neoprene dry suit
Neoprene suits are available in 2 types of material – standard neoprene or compressed neoprene. The standard neoprene makes the suit quite buoyant due to the tiny air bubbles within the material that help with the insulation – this in turn affects your buoyancy. With the compressed neoprene the material has been through a process of structural change that pre-compresses the air bubbles, which in turn reduces the fluctuation in buoyancy. One disadvantage to the compressed neoprene is that you would require more insulation in your undersuit due to the fact that the pockets of air in the neoprene have already been compressed which decreases the insulation in the suit.

Trilaminate dry suit
This material is made of three layers of material which include a harder wearing outer material, a middle waterproof layer, and a softer inner layer. One major downside to one of these suits is that it doesn’t hold much thermal insulation, so it is essential that you purchase a decent undersuit to wear underneath. Two big pros’ is that due to the compression of the material you won’t get any buoyancy fluctuations and the material is more forgiving, therefore it can accommodate for diver weight and size changes.

ATTENTION: Do not use a dry suit without the proper training.
Click here to find out more about dry suit diving.


These are worn underneath your dry suit to keep you warm. These are available in a wide range of thicknesses and materials. However, a general rule of thumb would be to layer up (wear 2-3 layers of thinner items) rather than 1 thick item. The reason being that air is a better insulator of heat so the more layers you have to trap the air the warmer you’ll essentially be – but bear in mind that doing this can affect your buoyancy. One thing you need to bear in mind is that you will need an undersuit that will move moisture away from the skin, preventing you from becoming damp and cold. The majority of undersuit manufacturers tend to be fast wicking to achieve this. On that note, cotton is a bad example of wicking moisture! Any sweat that the body produces gets caught in the material making it wetter and colder, which in turn will make you colder and wetter – therefore not a good material for undersuit wear.
Again, the time of year and water temperature/destination is a factor to think about when choosing your thermals. A good base layer will help to keep your skin comfortable and dry whilst a thin thermal layer should give you ample protection against the cold.  


You may want to add neoprene boots, gloves, and a hood to your wardrobe when shopping for a wetsuit – and gloves and hoods for a dry suit. They work the same way as the wetsuit but add protection to the areas that the suit doesn’t. Again, they come in varying thicknesses – all of which have their own pros and cons. For example, I feel the cold easily so I love my 5mm gloves and hood but I can hardly hear people when I have my hood on (especially if I’m on a boat!) and if I’m using my camera with my thick gloves I find it hard to operate it as your dexterity decreases with thicker gloves! With a dry suit there is an option to have dry gloves added onto the suit, these work the same way as the dry suit and keeps your hands dry and warmer.

Don’t forget!

Don’t just consider the average water temperature when buying an exposure. These tend to be taken from the surface, so bear in mind that the deeper you dive the colder the water will get. As well as a decrease in temperature the increased pressure will compress the neoprene in your wetsuit. As a result, the air bubbles will get smaller and in turn provide less insulation.
Your activity will also have an effect on whether you feel warm or cold on a dive. If you’re moving around a lot this will help generate more body heat and keep you warmer, whereas, if you’re on a slower dive or are stationary at most parts you’ll get colder quicker.
Also, bear in mind the air temperature. If you are on holiday and are wearing a fairly thick exposure suit (or even thin, depending on your tolerance) don’t stand around in the direct sunlight in the heat while you’re waiting for your next dive. This can make you dehydrated and ill which will ruin the remainder of your day – not to mentioned massively ruin your dive if you dive dehydrated.

We are a referral centre for O’Three. Not only do these guys provide a fantastic service but their products are spot on! If you go in there, don’t forget to mention our names and they’ll look after you 😊  You’ll notice that the majority of our team wear O’Three products – both in and out of the water, this just goes to show how much we trust and love the brand. Our school suits are also O'Three Semi-Dry's which have had great feedback from everyone who has ever used one. Check out out main cover photo for the blog - that 2 of our instructors wearing O'Three dry suits and 4 students wearing the Semi Drys.
Here's a recent photo of the dive club visiting O'Three in Portland for a lovely evening with the guys that included a tour of their shop & factory, an information presentation and of course a bit of food and some good humour :) 

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