Guide to Wetsuit Thickness
Water conducts heat a lot faster than air does, so while you would likely be warm outside in 24 degrees, the same temperature in water would require the correct exposure suit - in fact, any water temperature below 32 degrees Celsius is going to feel cold towards the end of the dive time!
Some people are susceptible to feeling the cold more than others or vice-versa - When you make your final decision remember to take this into account! This prompts the question, "What thickness suit do I need for my dive?" which is a good question indeed. However, there will always be a certain degree of personal tolerance. In this article, we will simplify the options for you.
With that in mind, the below recommendations are based on manufacturer specifications tested against the average diver and our own real-world opinions.
30 Degrees Celsius +
For most people, water above 30 Degree Celsius is warm enough to dive in just a swimsuit. However, we would recommend a Rash Guard to prevent any rubbing from the Scuba equipment, or even a full lycra suit for sun and stinger protection!
If you want to take some thermal protection, then a neutrally buoyant thermal layer or alternative neoprene product may be a good option.
28-30 Degrees Celsius
Generally, a 1,5 mm - 3mm wetsuit or shorty would meet the exposure protection requirements here. It is also a good idea to consider a 3mm full suit that provides physical and sun protection for your arms and legs.
If you preferred the neutrally buoyant option, this could be substituted for a thermal layer in a full suit or two-piece. They are also lighter than neoprene for keeping the suitcase weight down!
24-27 Degrees Celsius
A 3mm Full Suit is recommended with an optional thermal layer (Thermocline or Sharkskin) over the core. Your core (Torso) is the most critical area to keep insulated, so if you are adding a layer, make sure it's a core layer! Neoprene vests are an alternative to the thermal layers but make you more buoyant. Alternatively, if you are doing multiple deeper dives over an extended time, i.e. liveaboard holidays, even a 5mm wetsuit may be suitable for some divers.
21-23 Degrees Celsius
Now you'd want to switch into a 5mm full suit and again with the optional thermal layers. You will also want to be using boots and open-heel fins whilst also considering a thin hood. There is also a selection of heated wetsuit thermal layers to supplement your wetsuit.
18-20 Degrees Celsius
For 18-20 Degree Celsius, you would likely want a 7mm full suit; those extra 2mm will make all the difference! Optionally you could go for a 5mm full suit and thermal layer as above and a slightly thicker hood (3-5mm)
15-17 Degrees Celsius
It is starting to get cold now! A 7mm Suit is advised, along with an optional thermal layer. You could even go for thicker neoprene layers; however, remember to add on buoyancy by doing this!
A great option here is a Semi-Dry suit, a wetsuit with improved Neck, Wrist and Ankle seals, and a Dry-Zip to limit water ingress - It is vital with Semi-Dry suits that the fit is very good!
Below 14 Degrees Celsius
Below 14 Degrees Celsius, a Drysuit is recommended. See our article on Drysuits for more information on types and features and help choose which is best for you!
- How well a suit fit affects how well it insulates you, they should be skin tight to avoid water flushing around the suit.
- Repetitive diving (4 dives a day on a liveaboard) takes its toll on your bodies ability to heat itself continuously; it's recommended to bring an extra layer in case you start to feel the cold.
- Err on the side of caution if you are not sure! Being too cold underwater is very unpleasant but being too hot underwater is a rare occurrence.
- Check the water temperature for your destination at the time of the year you plan to dive. Some areas have a considerable annual temperature variation, affecting the exposure protection required.
- Remember to account for your tolerance!
- Some areas have Thermoclines, where the surface temperature may be warm. Still, underwater may be significantly colder - in this case, plan your exposure suit for the cooler temperature to avoid discomfort.