Is Scuba Diving Cold?
As you know, we cool much faster in the water than in the air. Even in a relatively warm sea, a diver will eventually feel the effects of the cold. The body will then launch a backup procedure. When the process fails, we enter hypothermia. But why cool down as fast in the water or is scuba diving cold?
Water is one of the largest thermal capacities in nature. All physical bodies must absorb heat to increase their temperature. It may seem like a truism, but it is a physical law. The amount of heat needed to increase the temperature of a body is called its heat capacity. The higher the heat capacity, the more this body needs to absorb heat to increase its own temperature.
Unfortunately for us, the water has a very high heat capacity. It absorbs and conducts heat about twenty times faster than air. The body produces heat faster than the air can absorb it, but it is not the case in the water. This explains why we will feel comfortable in the air at 70° or 71° F (21 or 22°C), while in water at the same temperature, we will quickly cold, without thermal protection.
It is estimated that water should be at about 93° F (34° C) so that a man of medium build, unprotected, does not feel the effects of cold. This varies of course from one person to another and even between men and women of the same size.
Why Don’t We Feel the Same Effects in the Cold When Diving?
We are not all equal when it comes to scuba diving cooling, because it depends on several factors.
The conditions of immersion are, of course, preponderant. The temperature of the water, the duration of the dive and the characteristics of the thermal protection (the diving suit) are decisive. But that’s not all. Indeed, we do not all have the same ability to produce heat.
Fat is Hotter Than Muscle
Well it’s wrong or at least not really true. Indeed, it is the muscle that produces heat when it is moving. The fat itself is an insulator. However, it turns out that – generally – overweight people tend to move less, therefore less heat. It is a bit like the snake biting its tail, according to a study by Anne Lonbes, director of research at the National Institute of Health and Medical Research (Inserm) .
Other Factors Favor Cold Diving
The fat / muscle ratio, however, does not explain everything. The feeling of cold can have many other factors. Thus, diving with an empty stomach will promote cooling. The physiological state also plays a big role, as does the psychological state. Diving by being a little helpless or depressed will increase the malaise and the body will have more difficulties to fight against the cold.
Do Not Ignore Warning Signals
The human body is an extraordinary machine. It has exceptional defense mechanisms, but it still has its limits.
Regarding the cold, the body will always seek to maintain the temperature of vital organs: heart, brain … this is called the central temperature. For this, it will first limit peripheral traffic. The extremities are the first to feel the effects of the cold. The toes, hands numb. At the same time, the tremors appear. It is an attempt to produce heat by moving the muscles automatically (hence the interest of having a good muscle mass). Ignoring these warning signals could lead to the next step: hypothermia.
What is Hypothermia?
Hypothermia occurs when the defense mechanisms have failed. The body gives up, somehow. Tremors stop, we enter a phase of mental confusion, fatigue and drowsiness that can lead to death. A doctor even explained to me that, in extreme cases, people were found dead from cold, in the nature, totally undressed, because in the final phase, one could also feel an extreme sensation of heat.
In short, the cold in diving must be treated with the greatest seriousness. It should be known that when the process is engaged, it can never go back. It’s always going to get worse. For this reason, if you are really cold, you must stop the dive. Prevent the rest of the team, go back together and warm up gradually.
How to Slow Down the Cooling
The suit: the first protection of the diver is, of course, his suit. It can be wet or semi-waterproof, 3 to 6 mm thick for temperate waters, 7 to 8 mm thick for colder waters, or even waterproof for very cold waters. The notion of cold or hot water can vary from one diver to another.
Gloves / slippers: protecting the extremities will reduce heat loss to hands and feet. Many instructors do not like it very much when their divers wear gloves that can encourage them to touch the fauna and flora with less apprehension. But here we are talking about comfort and safety.
The hood: we lose a lot of heat through the head. Personally, I never dive without it, even in tropical waters.
Some Preconceived Ideas About Scuba Diving and Temperature
The cold gas in the bottle helps to cool the body: False.
Indeed, if the sinuses and the trachea (which is the role of the trachea) warm the air that enters the body and therefore lose calories, they find them when the air leaves the lungs again, warmed by the body temperature.
Movement and physical effort warm up: True and False.
This is true if you also have good insulation to keep the heat produced. On the other hand, if not, more water is circulated on the skin, so there is no heat loss in the end.
Urinating in the warmed suit: Wrong.
Urine carries body heat with it. In addition, the short sensation of heat caused reduces or even eliminates vasoconstriction. The blood starts circulating over a larger part of the body and will eventually cool down.
We cool down less in rebreathers: True
The chemical reaction of air recycling produces heat. The latter therefore arrives slightly warmed up in the regulator.
Feel free to comment on this article and share your experiences with new divers answering the question Is scuba diving cold?
Cold Water Diving: Taking The Plunge Into The Cold
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For many divers, diving is a definite summer thing, associated with warm water, sandy beaches, and tropical fish.
Once winter hits, these divers either flee to other warmer destinations or simply hang up their kit and hibernate, waiting for warmer weather.
But it needn’t be so.
Winter diving can be every bit as amazing as summer diving.
But it’s not quite as easy.
Read on for considerations on kit and skills necessary to take full advantage of the “off season”.
Dive kit considerations
Cold water is a different setting than warm water from a dive kit perspective.
If you decide to try the cold waters, first make sure your regulator is in fact cold water safe.
The flow of compressed air cools in particular the first stage, which can cause it to freeze up and start free flowing. Most high quality regulators are approved for use in cold water, but check your reg before making the plunge.
Needless to say, you need warmer clothes for diving in cold water.
Thicker wetsuits or drysuits become relevant, and with this more weight to counter it the extra buoyancy. And thicker suits with thicker boots can also mean you need a larger fin.
Read more about diving gears here
Skill considerations
Diving with additional layers of clothes does feel very different if you’re used to diving in nothing but a shorty, so ease into it if need be.
Take a page out of the winter bathers handbook, and start early in the season gradually making you more and more used to the cold water and new kit. And dive places you know well, to keep the task load at a manageable level.
If you need to dive with a dry suit, and you’re not used to it, either take an actual Dry Suit Diver course. Or at the very least do a number of dives with an experienced dry suit diver who can help you get used to how a dry suit works.
Depending on where you live winter doesn’t just mean the weather gets colder it may also get darker.
If that’s the case, any dive beyond late afternoon will now be night dive, and in that case you need the necessary skills for this. And ideally, you should be a relatively experienced night diver, as the cold water does add to the total task load.
If it gets cold enough where you live for water to freeze, you’ll need to have appropriate training for this, too, if you intend to dive. Ice diving is a fantastic type of diving, but as it is a type of diving that takes place in an overhead environment, it does require training. So do an Ice Diver course to make sure you have the skills.
Best Way to Warm Up After a Cold Dive
There are many exceptional benefits to diving in cold weather and even wintertime. The water is clearer as there is fewer algae growth in the water because it can’t survive in colder temperatures.
This in itself makes it much easier to follow those most common scuba hand signals you’ve been working on. Furthermore, the change in temperature comes from different aquatic life and creatures. However, without a doubt, one of the biggest downsides of diving in cold temperatures is the warming up afterward.
Table of Contents
The Best Way to Warm Up After a Cold Dive
You will be taught how to wear the most effective combination of undergarments and a dry suit to get the best insulation during your dive when you attend ice diving and dry suit diving courses. And it’s likely by now you know why you should wear dive gloves when underwater in colder temperatures.
It doesn’t matter if you have the best scuba dive gloves, or not. After a cold dive it’s important that you deal with the heat loss you experience when you climb into the dive boat or reach the shore. At that point, your main goal is to get out of those cold and wet diving clothes and into ordinary, and warm clothes as fast as you can.
If you are planning on going on dives when the temperature is very low and its cold and are looking for help dealing with the change in temperature and how to get warmed up the most effective and quickest way, you’ve come to the right place.
In the rest of this post, we will provide you with a guide to getting hot when you’re shaking, wet and cold. The following guide, we should note, is based on you using a dry suit.
Step #1: Just Out of the Water
Once you are out of the water and have taken your scuba diving equipment off, remember to keep your hood and gloves on. Even if you are wearing a wetsuit and not a dry suit, you still have a reasonable amount of insulation protecting you from the low temperature of the air.
While keeping your hood on, dismantle your diving gear as much as you can and then place the unit where you are going to take the rest of your diving gear off.
Step #2: Get the Clothes Bag
It’s best to keep all your clothes in a waterproof bag of some kind, along with the fleece gloves and hat. Then try to start to open the bag keeping your wetsuit/drysuit gloves on. You don’t want to get your clothes wet, though, so don’t touch them yet.
Step #3: Taking off your Drysuit
Now, you are ready to take off your gloves, hood and then unzip the dry suit and get out of it as quickly as you can. The only thing you should be wearing now is that two-layer insulation we’ve already discussed.
Step #4: Putting Your Normal Clothes On 
Obviously keeping any underwear, you have on, remove the insulation trousers you are wearing and put your ordinary clothes on, along with socks and shoes. You can keep your insulation sweatshirt on unless it’s wet and then put the jacket on over the top along with the gloves and fleece.
Step #5: Disassemble the Rest of The Gear
If you are wearing gloves with removable fingers, expose them to help you easily disassemble any of your diving gear left. If you are diving at night, use a headlamp. Pack everything up and get yourself something nice and hot to drink.
The hat and gloves with wick any moisture away from your hair and hands, ensuring you warm up and dry quickly, while the material helps to keep you insulated. If you’ve finished your drink and put everything away, cover your fingers up and have another warm drink.
In theory, the process above will take from the first to the fifth step, approximately five minutes or even less, but it’s worth the effort.
Gear You Should Invest In When Cold Water Diving
It pays to have the right gear, equipment, and clothing at your disposal to make sure you can have a pleasurable experience exploring the great deep blue and then getting warm quickly when you’re out of the water again.
Invest in a high-quality jacket, specifically the kind mountaineers tend to use, one of those Hard-shell outdoor kinds. They provide you with excellent protection, but also have the benefit of lightweight construction.
Get yourself a two-part base layer, consisting of a combination of a thin layer that sits next to the skin on your arms and legs, with between one and two thicker layers on top. A great option is a pair of pants and a sweatshirt top. Look for items made with fast-drying materials like fleece. Skiing underwear, the kind that is basically long-legged pants and long sleeve shirts that fit closely to the skin.
A fleece hat and convertible fleece gloves often referred to as shooting gloves with the fingertips exposed as also useful essentials for cold water diving.
Scuba diving is more than a passion to me, it’s a part of who I am. Now, I travel and dive as much as I can, exploring the world, trying new dive gear, discovering dive destinations and reviewing them here for you. All while educating people of the threats our marine life and oceans face every day and what we can do to help defend it.
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Source https://oceanscubadive.com/warm-up-after-a-cold-dive/