Snorkel Mask

[zqvol]

Have you ever seen the commercial diver helmets?

 

Completely different system. Air is forced in, not sucked in, and forceably removed by the pressure

[SRF]

Uuh, not always.

 

There are commercial dive rigs with demand regulators. Typical scuba is demand regulator. Air is supplied when you suck. And expelled with you blow out.

 

Unless the system supplies air continuously, whether you breath or not, you will have the same issues. Pressure differential is pressure differential, no matter whether one is below or above ambient.

[CanadianMAG]

We have this one and love it!

 

https://amzn.to/2Gb7dai