Northeastwrecks once bubbled...
I have a snorkle. It lives in the bottom of my gear bag and comes out when I work classes. When I do real dives, I leave it in the gear bag.
I know this sounds stupid but I'm just curious. In a case where you didn't wear the snorkel when on the open water portions of a student's training dives, would you be liable if something went wrong? THere is a violation of standards (at least with PADI) if you aren't wearing a snorkel.