Some interesting feedback so far, thanks.

Yes I should have chosen some of my wording better, never leave a sub alone when you're talking about gags, or really most any kind of bondage or activity that could potentially restrict breathing. I should have worded it more to imply I'd be near by, but simply offering no stimulation (touch, words, etc). Safety first, a good core rule.

I'm also not surprised that some are into it and that it scares the hell out of others. I'm a pretty good visualizer. Borders on a meditation technique I suppose. I tried this for about five minutes earlier today (before writing the post here) on trying to imagine what this would be like... and I had to stop. It unsettled me a great deal. But really, that's what this would be used for. I wouldn't use this as a "normal" punishment... I was thinking more along the lines of a "you really screwed up and you need a lesson in obedience" kind of thing that I doubt I'd ever have to use more than once. As I said, I don't want it to be pleasant, though not neccecarily outright torturous. But I wouldn't want to use this as a "normal" punishment... it strikes me as having some potentially extreme mental consequences if used regularly on one who found it uncomfortable.

And I'd never ever attempt this on a claustophobic person, I don't think. I have a feeling that might well be as bad as locking them in a submarine and springing a leak on purpose.

Nikita (or any other subs who enjoy this activity) - could you express in words what it is you enjoy about sensory deprivation? Are there other activities you're atttaching to it? I'm always curious to hear the other side of the coin on something like this, even if the idea doesn't exactly tickle my fancy.

Really, a lot of what I wrote here and above was just thinking out loud on an idea I don't really know that much about, more so than any concrete plan to do this. Curious to learn. I agree that any potential punshments should more or less be settled on fairly early in a D/s relationship... and this is not one I'd force on someone genuinely unwilling at all, because I do find it potentially quite extreme if one chooses to make it that way.