Neoprene Wetsuits Series Part 1: Why doesn’t my wetsuit keep me warm anymore?

By Ingrid on 5/17/22

When I was certified back in 1994, I made sure to purchase my mask, snorkel, boots, and fins because well…I had to! It was recommended that I also purchase a wetsuit to avoid a suit that others had “peed” in and a dive computer because that is the one piece of gear you can’t learn while on the boat ride to the dive site. Fast forward 4 years and 60 dives and all the gear was still in great shape and working perfectly (by then I was able to purchase my regulator and BCD but that is another story). A year after that I started my Advanced training and quickly gained 40 more dives….and started freezing on dives that had previously been very comfortable. My suit was only 5 years old and looked perfect, so it had to be me, right???

There are several factors that affect becoming cold on a dive in the same temperature water.  The first is fairly obvious… our bodies change over time. Our muscle mass and fat composition change. Our metabolisms change. If you have a high metabolism you tend to stay warmer at first but if you have a low-fat composition, it’s hard to keep warm.  If you have a higher fat composition, it is easier to stay warm at first but over several dives, it's harder to heat your body mass up. If your body composition has changed and you are getting cold, that may be an indicator that you need a new suit (especially if the suit is too loose now). But is it the only thing you should consider?  Or if your body “hasn’t” changed what is another factor to consider?

IMG_1047(1).png A simple reason that you may be getting cold is that you are a better diver now!  That’s pretty cool right?! If you are more relaxed when you dive and have better buoyancy control, you aren’t using as much energy as you used to. This, in turn, prevents you from wasted movements and the warmth associated with those movements. You can always start bicycle kicking to get warm again but maybe a warmer suit is needed! I moved to a 5mm suit shortly after my instructor program and haven’t looked back. Your body composition and skills can affect your warmth but there are a couple of other things to look at too.

A common assumption is that my suit is old, so it doesn’t keep me warm. That in part can be true because neoprene wetsuits are made of rubber that can rot over time. It can happen to any product in a dry environment like Colorado, but it can also happen over time in humid environments. The fabric on the outside/inside of the suits keeps it looking beautiful but the suit itself feels like it shrank. It probably didn’t shrink (and maybe you didn’t grow) but rather the rubber became stiffer due to age, so it won't stretch like it used to. At its worst, the neoprene itself will delaminate from the fabric and essentially break apart letting water gush in.  This is a major failure that is obvious and indicates that you need a new suit. Therefore, the age of a suit mainly causes discomfort due to lack of stretching and potential full breakage.  This is what could cause you to get cold when the suit looks and “feels” perfect, and your body “hasn’t” changed.

The insulation of a wetsuit relies heavily on how many dives you have accrued in the suit! This is the least obvious of all the possible scenarios and yet is one of the most important to consider. Neoprene wetsuits that we dive in are subjected to more abuse than surface sports. They undergo all the pressure changes that we do without the benefit of a regulator compensating and adding air to prevent the bubble spaces from crushing. That means that every dive we use our suit on, it compresses thinner at depth. Once you come up to the surface the neoprene bubbles expand back to the size they were originally….for a while. Over time, the neoprene itself wears down and those bubbles no longer want to expand back to their original size, so the suit loses thickness or insulation permanently. Shockingly, this can happen as early as 60 dives. That suit I had started as a 3mm suit, and when I compared it to a new 3mm suit it was ½ as thick! The older non-stretch neoprene doesn’t compress as quickly but no one wants to wear it anymore because it is so uncomfortable. Low-end neoprene that is stretchy compresses quickly (30 dives), which is why most dive stores only sell dive quality neoprene suits and not the sporting goods suits. That neoprene is perfectly good for surface sports and will retain its thickness because it is not compressed but take it on 30 dives and your suit is toast. Although my suit looked perfect and in “new” condition, it was easy to tell that it had lost insulation. IMG_6850.png

Nowadays, I always buy a 5mm suit and plan for the compression so my suit winds up a 3mm after 60-80 dives and I can use it in the tropics. I realize that my metabolism has slowed down, I certainly have more padding than I used to back in 1994, and my skills have gotten better since I first started, but the main factor in how cold I get is if my suit is as thick as the arm says it should be!

A lesson to the wise…When you come back from a trip think about your gear….was your suit warm enough, did you have everything you needed, did everything work well? And if it didn’t, please don’t wait until right before your next trip to fix the problem!


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