Comment by rkagerer | Hacker News Reader

Comment by rkagerer | Hacker News Reader

There's actually another air space that you need to equalize while diving — the inside of your scuba mask. Don't forget to add air to it as you go deeper, or that thing will awkwardly squish your face.

It would be more accurate to say "suck out" rather than "squish". The pressure is lower in the mask. So the cavity acts like a vacuum trying to pull out your eyeballs.

Yes, the ridge of the mask may feel like it's crushing into your face (and cause bruising to the soft tissues it contacts), but I gather the broken capillaries and bruising in your eyes from the suction are what pose the bigger risk.

The condition is called mask squeeze (or facial barotrauma) and I experienced it once shortly after I got a Hydro Optix mask, which has a larger volume of air compared to normal masks. It was before I appreciated how much extra air you need to blow out through your nostrils while equalizing it, and occurred on a descent that went a little faster than I preferred as I was paired up with a less experienced diver who had some initial buoyancy issues and I decided to stick with her in case she needed help rather than slow my own descent.

It was scary at the time (eyes got bloodshot red like a vampire), but the good news is most cases heal up fine with time.

The Hydro Optix is a great mask if you use it right (shame they went out of business), and SCUBA is an incredibly rewarding sport if you train properly and stick within your capabilities (happy to say that diver doubled down on the sport instead of giving up, got some more training, and now has hundreds of dives under her belt and is a highly competent divemaster).

Good reminder if you feel pain while diving to listen to it and surface to figure out what's wrong. Don't be tempted to power through.

On that note, particularly if you're a newer diver, learn to avoid the temptation to surface quickly when you run into an uncomfortable situation. In most early rec diving that's absolutely an option, but as you find yourself interested in deeper dives, wreck penetrations, caves and other sites that are both an incredible experience and higher risk that's where accidents happen.

Focus on being able to calm yourself, trust your dive buddy, recognise signs of impaired cognition in both yourself and them, and work through whatever situation you find yourself in as a team. It's not a solo activity and any action you take impacts both of you.

Good advice - I wish diving leaned a bit more into managing buoyancy early on. I used to sometimes dive tail for a dive instructor doing group instruction if there was a shaky diver - some stressful moments. My ears hated it because I naturally am a slow decend/ ascend diver

Have you ever tried taking Sudafed before a dive to see if it helps your ears? I've had minor MEBT (and plenty of discomfort) without, but so far I can shoot right down after taking it.

From the research I did before making the decision to try it, results are very mixed (there are plenty of anecdotes, but studies are few) [0] but it seems like as long as you try it on land first (on a non-diving day) to ensure no side effects, there's not much reason not to give it a go [1].

[0] https://pubmed.ncbi.nlm.nih.gov/1610044/

[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3931412/

This is interesting. I've never given it much thought (and didn't know MEBT was a thing), but I've experienced the same discomfort while: SCUBA diving, skydiving, ordinary air flight descent, and even some hilly car driving.

Doc says there's nothing wrong or clogged etc about my eustachian tubes. It's easy enough to manage (except skydiving, where the pressure change is too fast and not under any meaningful control of mine!), but if pseudoephedrine would make things less distracting during SCUBA, I'm interested.

Thanks for the links!

It’s very important to note that pressure plays a role in how quickly the body processes out the medicine. A dose might last 6 hours on land may last much less under pressure. One significant danger to this is a decongestant wearing off unexpectedly early while underwater, resulting in congestion a depth and preventing equalization upon ascent. This could result in a barotrauma often called “reverse squeeze”.

Definitely worth noting, but personally I've never had any discomfort during ascent even prior to using the decongestant, and based on some other comments here, that seems to be because our ears are better equipped to readily equalize when over pressurized than under... approximating a check valve, I suppose?

I use the generic (CVS brand) 12-hour extended release 120mg about an hour before diving, then two dives with a surface interval between, so I'm only relying on about 4 of those claimed 12 hours. I'm not sure the magnitude of the effect you warn of regarding accelerated processing, but there's a good margin to work with. There's also a 24hr formulation available.

I’ve done the same. But my point is the “specs” are not well documented and a novice may not have considered this factor.

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