I guess there‘s no definitive answer, as there are a number of factors at play. There’s technically no reason why a “sports” watch rated to 100m can’t be used for recreational diving with air, as long as the seals and gaskets are regularly checked/replaced/lubricated and then pressure tested. I’d also want a screw down crown to avoid accidental operation.
That being said, I’m pretty careful with my watches, so I would probably want 200m or more 😂

Hi everyone! Hope you’re all doing well. Rocking my Doxa Sub 300 today on the stock BoR bracelet. Looking forward to chatting with you guys. 
 

PS thanks for the invite, Max!