Why Does Scuba Diving Make You Tired?

So, whether you’re new to diving or you’ve been diving a while, the reasons you may feel more tired than normal after a dive aren’t quite as obvious as you may think.

In this article, I will take you through the causes of post-dive tiredness and how you can avoid them. Interestingly, the reason you may feel fatigued after a dive could be down to how long you have been a diver


Thought so…let’s dive straight in!

Why Does Scuba Diving Make You Tired?

  1. Physical Exertion
  2. Mental Exertion
  3. Water Temperature
  4. Lifestyle
  5. Decompression Sickness

Ok, so, they are the main reasons for post-dive tiredness, now let’s explore them in more detail and find out what we can do to avoid needing a nap after you surface.

What are the Causes of Post-Dive Tiredness?

Physical Exertion of Scuba Diving

When we see videos of people scuba diving it all looks laid-back and tranquil, but in reality, even on the calmest of dives, you are in motion for 40-60 minutes. Ok, so you’re not swimming at the pace of an excited Tuna, but you are moving.

Not only that but you are moving through a medium 838x more dense than air, you are trying to breathe while you’re doing it.

*Seawater average density = 1027kg/m3 Density of air 1.225kg/m3 (1027/1.225 = 838.37)

The density of seawater and the pressure of the water at depth added to the resistance of your wetsuit and your regulator all add up to an increased workload for your diaphragm and intercostal muscles (the muscles that move your ribcage when you inhale and exhale.

As anyone who has done any exercise, ever, knows that the harder you work, the more energy you use and thus, the more tired you get.

So Scuba diving is a good workout. Simple right?

But…is this the only reason you are tired after diving?

Mental Exertion of Scuba Diving

Thinking requires energy.

If you’ve ever studied for a test or had a very tight deadline at work, you are probably familiar with how excess concentration can make you sleepy?

Humans are not designed to be under water, we are land animals. So in order to spend time under water (without drowning…obviously), we require scuba equipment.

That equipment requires concentration to use, especially if you are a relatively new diver. There are lots of things to think about; buoyancy, hoses, how much air you’ve got left etc.

That added to the fact to the basal understanding that you are not designed to be there, it all adds up. The more you have to think about, the more energy required.

As you become more experienced, the concentration needed is reduced (as things become learnt actions…think muscle memory).

This mental exhaustion is therefore much more prevalent in less experienced divers or more experienced divers learning more expert dive skills (or those working underwater).

scuba diver swimming over a reef

What Effect does Water Temperature have on Divers

Your body works hard to maintain your core body temperature (37ºC/98.6ºF) and you use a lot of energy to maintain it. The further you go above or (in this case) below this temperature, the more energy you use.

For instance, the average sea temperature in the tropical Caribbean Sea is 27ºC, a whole 10ºC lower than body temperature.

That’s quite a bit of extra work your body is doing!

…and then there’s the effect of depth.

As you descend below the surface, less of the sun’s energy penetrates water, the deeper you go, the colder it gets, ergo, the more energy you expend.

These two elements added together result in your body working overtime. No wonder you’re tired after a dive!

Lifestyle Factors That Could Make a Diver More Tired After a Dive

As with everyday life; lack of sleep, jet lag and alcohol consumption the previous evening, can also exacerbate post-dive tiredness.

Decompression Sickness

Decompression Sickness (The Bends) affects divers when they ascend to the surface too quickly or without a safety stop. It is caused by a build-up of Nitrogen bubbles in the blood vessels and tissues that expand as you come to the surface (caused by the external pressure decreasing).

One of the symptoms of decompression sickness is, you guessed it, fatigue!

If you have ascended to quickly or you forgot to do a safety stop and you you are feeling tired (along with the any of the other symptoms below, seek medical attention urgently!

Symptoms of Decompression Sickness

  • Less severe symptoms.
  • Fatigue
  • Loss of appetite
  • Headache
  • A vague feeling of illness
  • Severe Symptoms
  • Headache
  • Confusion
  • Trouble speaking
  • Double vision

How to Avoid Post-Dive Tiredness

  • Get enough sleep the night before diving
  • Minimal (ideally zero) alcohol consumption the night before a dive
  • Have a good level of cardiovascular fitness
  • Wear appropriate wetsuits for the water temperature.
  • Experience; You have less to think about and are less likely to make mistakes while ascending.

Make sure you relax and recover after a long day of diving!

man relaxing in a hammock

Don’t Forget Your Dive Insurance!

Before you go out on any dive trip or holiday, it is essential to make sure you have insurance that covers you if something goes wrong. Check out our dive insurance article for more information.

Or go straight to these dive insurance company websites:


Diver Alert Network (DAN)

If you liked this article, please follow us on Instagram, Twitter and like our Facebook page


So there we have it, you know why you may feel excessive tiredness after scuba diving and how to avoid it.

I hope you found this useful, be sure to check out more articles on the website.

Please share this article using the social media buttons!

Paul Fulbrook

Paul Fulbrook is a writer, scuba diver, ex-science teacher and marine biologist. He has a passion for coral reef biology, diving on coral reefs and writing about diving. He also loves cats and his children (sometimes).

Recent Posts

Seraphinite AcceleratorBannerText_Seraphinite Accelerator
Turns on site high speed to be attractive for people and search engines.