

Yes, closing your sinuses is a natural reflex response for humans, and people have greater or lesser at will control over it.
The nose holding for swimming is more about how strong that sinus closure is and endurance. People with larger sinus openings have a more difficult time keeping them closed and resisting pressure like water entering from jumping into a pool. Also some people have a hard time keeping them closed for any prolonged period.
In other words, you just have totally ripped sinuses breh.











Thinking about implementation, it seems like tooltips would be a great way to handle this. Linking out from the tool tips to some kind of more comprehensive outside IT/cybersecurity resource would be a good bonus. Tool tip text generated by llm could take some of the heavy lifting.