Never exhale under the dive

[JanK]

May I ask why do you need to have the snorkel out of your mouth? In all the snorkeling I've done for the last 35 or so years since I was a kid I've always kept the snorkel (always a simple J without any purge valves or top valves) in my mouth and never had a problem. Just after start of an ascent I blow a little air into the snorkel until I hear it bubbling out and then I keep my head tilted up with the snorkel pointing downward, so the air in the snorkel expands and always keeps the snorkel free of water. Just below the surface I start the real exhale and when I breach the surface I just tilt the head forward and breathe in. If I just dip under the surface, swimming more or less horizontally, I just forcefully exhale and shoot the water out. And I hate the snorkel flopping about my face as I move around.

The only real problem that I've been having lately, after starting scuba diving, is that for the first few freedives I need to remind myself not to breathe in, since there isn't a tank attached to the snorkel (and yes, I wait for full desaturation after scuba to go snorkelling).

 

[Akimbo]

The reason that freediving courses teach you to spit out your snorkel is incase you blackout shortly after surfacing. Conditions called Shallow Water Blackout (SWB) and Samba occur when the oxygen level in your bloodstream has dropped enough to cause hypoxic blackout, even though you may have already taken your first breath. There is a primal reflex that causes you to close your mouth when your face is wet, at least for a short time after blackout. However, that reflex is circumvented with a snorkel in your mouth — providing an open canal straight into your lungs.

I encourage every freediver to investigate this site:

Welcome to DiveWise - the Freediving Education Initiative

Google finds lots of information and videos on SWB and Samba that are very interesting and sobering.

 

[JanK]

Ah, I knew about the SWB, but not about the fact that it can occur after taking a breath, and didn't know that the reflex also makes you close the mouth. But yes, both make sense. And I just learned a new usage of the word samba.

And in the meanwhile I've done some Googling and have also learnt that the jaw can spasm closed in blackout and a rescuer could have problems providing artificial ventilation.

Thanks for the info.