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!
This prompts the question "What thickness suit do I need for my dive?" which is a good question indeed. In this article we will simplify the options for you, however there will always be a certain degree of personal tolerance, some people are susceptible to feeling the cold more than others or vice-versa - When you make your final decision remember to take this in to account!
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 swim suit although 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!
28-30 Degrees Celsius
This could be substituted for a Thermal Layer in either a full suit or two piece if you preferred the neutrally buoyant option, they are also lighter than neoprene for keeping the suitcase weight down!
24-27 Degrees Celsius
A 3mm Full Suit is recommended here with an optional thermal layer (Thermocline or Sharkskin) over the core. Your core (Torso) is the most important area to keep insulated, so if you are adding a layer make sure its a core layer! Neoprene vests are an alternative to the thermal layers, but will make you more buoyant.
21-23 Degrees Celsius
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!
15-17 Degrees Celsius
A great option here is a Semi-Dry suit which is Wetsuit with improved Neck, Wrist and Ankle seals along with a Dry-Zip to really 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 along with help choosing which is best for you!
- How well a suit fits 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 continuously heat itself, its recommended to bring an extra layer incase you start to feel the cold.
- Err on the side of caution is 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 large annual temperature variation which will affect the exposure protection required.
- Remember to account for your personal tolerance!
- Some areas have Thermoclines, where the surface temperature may be warm but underwater may be significantly colder - in this case plan your exposure suit for the cooler temperature to avoid discomfort.