As those involved on the production side are, or should be, aware, repeated submersions present some challenges to the actress.
As was pointed out by the first reply here, the actress must work fairly hard at sinking once she is past the buoyancy point. The thicker (which also means heavier) the mud the harder she must work. If the scene is on the melodramatic side, she must then transition to working in the opposite direction if there is to be more than one submersion. Then, once she is above the surface she must go back to sinking without wiping her eyes. This latter transition can be covered by a cut to the other angle if there are two cameras but continuity is tricky. Such a cut also lets the actress catch her breath. If the scene is an erotic one the need to avoid wiping the eyes is not so important.
The work to submerge can be reduced considerably by making the mud wetter. This, however, increases the risk that mud or muddy water might get in the actress's eyes. Depending on the kind of mud that event almost certainly ends the scene but it could also end the shoot. Clay, in particular, can be very irritating if it gets in the eye and wetter clay is a LOT more likely to do that.
I do agree that a melodramatic scene with two or more submergences can be pretty interesting. Its also rather risky.
On the topic of extending the apparent submergence by the use of bubbles injected through a pipe or hose, I think that can be effective. I think the first time that was done was here at Studio 588 although by a different producer, and I have done it many times since. I think, however, it is even MORE effective when the actress herself can produce the bubbles. That requires very good cardiovascular fitness (not to mention presence of mind - ok, I mentioned it) and is a STRONG point in favor of actresses who do not smoke.
Duncan Edwards wrote:I've always been a fan of the extended submersion in sinking scenes. Extending the struggle with post submersion bubbles or splashing adds a lot to the end for me and often, but not always, a repeated struggle back to the surface. For some of us the best struggle is trudging through thigh deep mud while for others it's about a struggle for life. Often a struggle that we know is going to end in failure anyway. I suppose this makes such finishes more like torture in reality but I'm very cool with that most of the time. So what does anyone have to say about this? How do you feel about watching the hapless victim fight back to the surface only to sink under again? How many times? What about going under and clawing their way out to safety?
Always wondering how typical my preference is.