Achieving a good seal while keeping your mojo beard ... There is more than one way to skin this particular cat, so lets look at our options, shall we?
1. Grease up.
Vaseline, mask seal, lip balm, silicone grease… the list seems endless. Get something that is goopey and isn't water soluble and slap it on your upper lip. With modern, silicone skirted diving masks there's no need to be nervous that your grease is going to eat your mask (unless your desire to bring back the fashions of the past extends to classic rubber skirted dive masks!) All of these options work the same way – the viscous grease fills in the gaps between your mask, facial hair and face and allows your mask skirt to do its job and make that awesome water tight seal. While effective, they do leave you needing to clean up afterward!
2. Trim down.
If you're willing to make some small adjustments to your 'tache you can make your mask seal up just fine. Don't worry, you don't need to bring it down to a pencil moustache (though I'm sure you'd look like a classic Hollywood star if you did…). Just trim away the top 5mm or so just under your nose and you're good to go. You might also need to adjust your mask and strap positioning to get things sitting just so.
3. Tool up.
There's a mask for every face… there may well be one for your facial hair too! Take your time, try on every different one you can and see what works! If you lip caterpillar is going to be a permanent feature if might be time to look into investing in a new mask better suited to the new you. Or for you scuba divers why not look into a Full Face Mask?
So there we go, four options for keeping your mask seal firmly in place without sacrificing that magnificent moustache of yours. How do you keep the water out of your mask when you're diving?