Somewhere way back in your training, you were probably introduced to the Incident Pit. It’s a fairly dramatic diagram with the words “fatal” and “death” appearing at the bottom. The concept was meant to inspire you to deal with problems early, keep control and stay safe, with the tag line “Don’t fall in.” This always seemed to be a slightly strange thing to say to divers, who are destined to fall in (to a body of water) quite deliberately. Other than encouraging you to run through your own personal risk assessment for a dive, that’s about all the standard training material has to say about pre-dive thinking.
​
In many sports the technique of visualisation is used to help elite athletes achieve their potential, and there’s good evidence that it works at lower levels too. Visualisation is the process of creating a mental image of what you want to happen or feel in reality. An athlete could use this technique to picture crossing the finishing line first. For a diver there is clear potential to visualise a relaxed, in control dive and achieve a state of calm and well-being before a dive. In fact, most people naturally tend to think through and rehearse what’s about to happen to them. So quite possibly you have started to think this way already.

Sometimes these preparatory thoughts can be plagued with recurring images of past mistakes or near misses, and that’s not conducive to ensuring the success of the upcoming dive. It can be more helpful to actively direct your pre-dive thoughts and control those images in your head. And the visualisation probably needs to be more than just a visual experience. To really be successful, you would need to focus on all the senses; the rush of cold water, the smell of the sea, the feeling of pressure on your legs as you enter the water, the sound of your bubbles.

When you visualise the successful dive, you are stimulating the same regions of your brain as you do when you physically perform the same action. So, thinking the dive through, with all it’s stages, is a way of conditioning your brain for a successful outcome. Perhaps the visualisation starts before the dive, right back to the preparing your equipment. And the beauty of this preparation is that you could be doing it anywhere. Picture being on the bus thinking about packing your kit for the weekend.

What if we extend this to thinking through the different situations that may arise underwater? Rather than the scary prospect of the Incident Pit, why not challenge divers to visualise their response to common problems? What would they do if their torch fails on a night dive? It’s too easy to just say “I’d get my back up torch out”. In order to visualise it you would have to work through being able to open your BCD pocket (feel the zipper in your hand, hear the zip and feel as it bumps along the teeth), feel through the gloves for the piston clip, unclip the torch lanyard from the D ring, feel the lanyard in your hand etc. Which pocket? What else in in there to avoid dislodging? How will the torch feel in my hand? This is a far more powerful psychological technique than a glib “Get my back up” response.

For divers just starting out on their diving journey, visualisation can be an excellent way to deal with the nervous trainee. Try to remember the first time you put all your dive kit on. How tight did your neck seal feel? How restricted was your movement? These are things we all take for granted now. We have done it often enough that we barely register the sensation. I think there is a real value in talking through that first dive. This is not part of your SEEDS brief, this is so much more. Find a quiet space, sit down and step your way through the dive, start building the neuronal connections in a positive way and help boost performance.

It doesn’t matter how carefully you monitor your fluid intake before a dive, or how close to dive time you leave the last toilet visit, we have all got out from a dive ready to rugby tackle anyone standing between us and the toilet. It’s well known that going for a dive causes an increased need to urinate. There are some interesting physiological changes that come to play. Immersion and temperature changes cause a narrowing of the blood vessels in the extremities. This results in an increased volume of blood to the central organs which is interpreted by the body as fluid overload. This causes the production of antidiuretic hormone (ADH) to stop, signalling to your kidneys that they need to produce urine to lower the blood volume. So even if your last toilet visit was only minutes ago, you can quickly find yourself feeling the need to go again.
​
It’s almost impossible to give an exact measurement for the volume of the human bladder as everyone’s ability to hold urine varies. Normal adult bladders hold between 300 and 400ml but can hold up to 600 or even 1000ml in some cases. The need to urinate is stimulated by the expansion of the bladder which triggers the Micturition reflex centre in the spinal cord. Most adults will feel the need to urinate when their bladder is only around a quarter to a third of its normal capacity. In normal circumstances, adults will feel the need to empty their bladder about every 3 hours, but as divers we know the effect that immersion plays.

There’s always a big debate in the wetsuit diving community about whether peeing in a wetsuit is acceptable or not. In a drysuit, the debate becomes somewhat redundant unless you have a P-valve fitted. But is there any danger to ‘holding it in’? When you first feel the need to pee, your bladder probably has quite a way to go before it’s completely full. As your bladder fills up the muscles around it will contract to keep urine from leaking out until you’re ready – just make sure you can get out of your suit fast enough!

The dangers of holding your pee are mostly cumulative, so the occasional episode probably isn’t harmful. However, if you are diving frequently and often find yourself ignoring the need to pee you run the risk of urinary tract infections, urinary retention (the muscles can’t relax even when you want to pee) or bladder atrophy (leading to incontinence). But for most people, you can hold your bladder full for a few hours without serious complications, even though its uncomfortable.

If you dive in a wetsuit, you can of course make the call as to whether you pee in your suit or not. The old saying is that 50% of divers pee in their wetsuits and the other 50% are liars. So whichever camp you fall into, just make sure you flush your suit through before you get out of the water and start to take it off, and please wash your suit thoroughly between dives.  If you’re a drysuit diver, there’s always the option of adult nappies to ensure that you can relieve yourself. If that seems a little retrograde, or as you march middle age a little too prophetic, then perhaps a P-valve is an option.

Not surprisingly there are hazards associated with P-valves too. Ignoring the issues with getting a stick-on condom or the female cup attached successfully, so that the urine does actually enter the tubing to leave suit, there are reported cases of urinary sepsis. The tubing used to connect the urine to the P-valve is the ideal breeding ground for Pseudomonas bacteria, and it only takes a small amount of backward flow to introduce those bacteria into the body. If you think rinsing your wetsuit is a bit of a faff, syringing antiseptic through P-valve tubing should give you some perspective.