several reasons... the point is to practice putting on a mask underwater in case the mask is knocked off inadvertently. Just a couple of weeks ago, I was in the water with a Dive Master that purposefully took off his mask and continued on the dive. I asked him about it when we surfaced - he said it helped clear out clogged sinuses. I'll be posting that video later this week. Also - practicing drills is never a stupid thing to do. It sharpens a diver's skillset.

Agreed! Great explanation. @@SeaThisDiveChannel