I've actually found it is MUCH easier to be maskless, if someone sneaks up behind you and just snatches the thing. There are few things in diving I loathe more than the signal to remove my mask.
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Where were you diving ... the Passaic River?
Oooh...one fine cesspool. Where'd that come from?--nowhere near Pugetropolis...
You may want to ask what instructional benefit is achieved by the surprise mask yank-off. What real life scenario are you recreating?
When I recertified, the instructor had us individually kneel on the bottom of the pool and then he came in behind us and ripped our masks off. I wear contacts, can see people, but not clear enough to pluck their eyebrows. I was told it was a skill that their shop decided to incorporate into the training.