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I'm soon to embark on a chilly scuba dive around 5-7C at 18m, of which we'll be wearing 7mm semi-drys with shorties. The next thickest I think is actually a drysuit for really cold waters, but not sure if there is a thicker wetsuit. However this got me thinking then about diving in warmer temperatures as well as colder.

For what temperatures would you wear different thicknesses of wetsuit, including none, and shorties?

Edit: We did drysuit in the end for these temps.

  • Here in Canada I have seen people diving cold water with the 7mm, personally I use the 7mm even in warmer months. For around 2-5C I saw people being ok with a 7mm, mitts, hood and boots. It depends a lot on your tolerance to cold and how long the dives are, probably you wont be in the mood for a second dive that day... when you get out feels even colder... some are ok with it, some try and give up, and there is people who passed to a drysuit and wont look back. Seen some add a vest, lots of buoyancy that way though. Rather be sure your regulator and bc inflater can take cold temperatures – Erik vanDoren Feb 22 '16 at 17:01
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    Also a perfectly fitting wetsuit makes a difference rather than an "almost there one" – Erik vanDoren Feb 22 '16 at 17:06
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    Even though there would be variance due to personal tolerance, it would be interesting to see a table of recommended temperatures for wetsuits like they have for sleeping bags. I've always guesstimated in the past. – Erik Feb 22 '16 at 18:11
  • Any thicker and you won't be able to move in the suit without water flushing everywhere you bend. – ShemSeger Feb 22 '16 at 20:21
  • In Waterton Lakes here in Canada most people use Drysuits for scuba diving. – ShemSeger Feb 22 '16 at 20:23
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Wet suit thickness is a very personal thing. I for instance dive in a 3mm shorty in 15C and higher and 3mm one piece for temperatures under 15C and above 6C

Remember that you can also layer. So I would say a Dry Suit with thick under garment or a 7mm wet suit with a 3mm chicken vest underneath. Some nice thick gloves and hood and if you really cold then wear a 2nd layer of 5mm over the top.

Here are some good guidelines.

"Shorty wetsuits and dive skins are generally used in warm tropical waters with temperatures of 75°F- 85°F (24°C- 30°C) and above, depending on personal preference. Dive skins do not provide thermal protection, but do provide protection from accidental stinging by sea lice, fire coral and other small marine hazards. Shorty wetsuits provide a modest amount of thermal protection for core body areas.

2mm - 3mm (1/8 in.) wetsuits are generally used in warmer waters with temperatures of 70°F- 80°F (21°C- 27°C) and above, depending on personal preference. During cooler weather, additional warmth can be achieved through the use of a 3mm hood, addition of a 3mm hooded vest under the wetsuit and/or use of a 2-piece 3mm wetsuit.

4mm - 5mm (3/16 in.) wetsuits are generally used in cool waters with temperatures of 60°F- 70°F (16°C- 21°C) and above, depending on personal preference. During cooler weather, additional warmth can be achieved through the use of a 3mm-5mm hood and gloves, addition of a 3mm-5mm hooded vest under the wetsuit and/or use of a 2-piece 5mm wetsuit.

6mm - 7mm (1/4 in.) wetsuits are generally used in cooler waters with temperatures of 50°F- 60°F (10°C- 16°C) and above, depending on personal preference. During cooler weather, additional warmth can be achieved through the use of a 5mm-7mm hood and gloves, addition of a 5mm-7mm hooded vest under the wetsuit and/or use of a 2-piece 7mm wetsuit or semi-dry 7mm wetsuit. Semi-dry wetsuits have Neck seals, wrist seals and ankle seals that adhere to your skin to minimize water entry."

Wet Suits for Temperatures

More Wet Suit Thickness Tips

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    This looks great, but can you add the main points from the links incase they go down? – Aravona Feb 23 '16 at 8:20
  • @Aravona Updated – AquaAlex Mar 12 '16 at 18:47
  • Hi AquaAlex! I appreciate that you provided the information @Aravona asked for. As it turns out, your second link is down! I know you already put the information into your answer, but I'm just letting you know in case you want to replace the link, or delete it. Thanks! – Sue Mar 17 '18 at 23:55
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It's a question of the right tool for the job. For diving in temperatures below 14 degrees Celcius, a drysuit is best. When diving below 7 degrees a wetsuit really isn't the right tool for the job and is dangerous as you'll be extremely cold and will suffer on the surface. Even diving a 7mm wetsuit with a shortie over the top still isn't sufficient when compared with a drysuit.

A drysuit also gives you additional or backup buoyancy should your BCD fail.

Even when the surface temperature is 25 degrees, a drysuit is useful as it's a lot colder at depth or when submerged for a long time. You will vary your drysuit undergarments depending on the temperature.

For dives in very cold water the less you're exposed to the water the better. For the same thickness, dry gloves keep your hands much warmer than wet gloves as there's no liquid to conduct heat.

If you absolutely must dive in 5 degree water in a wetsuit, it's vital that it's a semi-dry where your wrists, ankles and all zips are sealed to avoid flushing of cold water which could cause the 'gasp' reflex. You must also make sure that you can get into a warm location to change and get out of the wetsuit as soon as possible after the dive. You do not want to be exposed to wind chill in a wet wetsuit.

Getting cold is at best uncomfortable, it shortens your dive, it is really unpleasant, and can put you at great risk, not least of giving up diving.

For UK winter diving (typically 5 to 7 degrees), virtually everybody dives with a drysuit for those reasons. I dive with drygloves and a heated vest which I can thoroughly recommend especially if you're doing long duration dives.

  • We dived in drysuits in the end with 1.5mm gloves and 3mm hoods. Though when we did our summer dives in 21C loads of people were in semi-drys and wetsuits, even in the UK. – Aravona Jan 17 '17 at 10:03
  • I was diving in a cold quarry last week (January, UK) where there was ice on the ground and around freezing point all day with water temperature at 8 degrees. Aside from the open-water swimmers (!), there was a young woman who dived in a wetsuit and who was violently shaking with cold after getting out. Whilst we all used to dive with wetsuits, technology has moved on and drysuits have taken over. – GlennG Jan 18 '17 at 8:31
  • Yes but in summer that's not always the case I'm saying, in 21C water you don't necessarily need a drysuit (OW max depth is 18m, which at a lot of UK dive sites limits you to around 12m) and a wetsuit or semi-dry will do if you're not qualified for Drysuit - most swimming pools in the UK are around 20-23C. – Aravona Jan 18 '17 at 8:34
  • Absolutely; many people choose to dive with wetsuits in the summer when the sea is 18C. Exposure protection is like sleeping bags: one season, three seasons or four seasons. – GlennG Jan 18 '17 at 8:57

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