What is the best practice when spearfishing/freediving/snorkeling: Retaining the snorkel in the mouth in the diving cycle or remove it before the duck dive and put it back once in the surface?
Personally, I always remove the snorkel. If I am close to my limits, that way I do not have have to purge the snorkel upon surfacing. But am wondering if there is any data on this.
I found this video with spearfishing champions and the majority (if not all) wears the snorkel when surfacing.
I keep the snorkel in my mouth during 'duck dives'.
When nearing the surface, I look upwards - that makes the snorkel point downwards, and just a small trickle of air can purge it, since the air is 'trapped' inside the downwards-pointing snorkel.
Just when surfacing, tip the head, so you are looking downwards again (the timing may take a little practise) - now with a clear snorkle for breathing.
You can also get a snorkle with a valve, that makes purging the snorkle much easier, without using the above-mentioned technique.
Short Shallow dives maybe its OK to have the snorkel in your mouth, but deeper dives its important to take it out before diving. This is because losing consciousness becomes an increasing risk and having the snorkel in your mouth will exacerbate this situation. Removing the snorkel is common practice among experienced breath hold divers.
https://scubadiverlife.com/tips-lowly-snorkel/
How you define short and shallow is up to you and your perception of risk.
This film may highlight the point. Viewers may find this upsetting.
All this aside. SE is not the platform for seeking reliable information on this subject.
