In Peter Jackson's Hobbit movies, there's a scene in which the heroes attempt to kill or entrap the dragon Smaug by covering him in molten gold.
An answer on SciFi.SE claims that this is physically implausible due to the density of gold:
...even if Smaug's body was solid lead (11 g·cm−3), he would easily float on liquid gold (19 g·cm−3)....
As noted in the answer, the scene does not actually show Smaug falling into the gold, but rather being covered in it as a giant gold statue melts, forms a "wave" of molten gold, and envelopes him:
...Smaug sits on the ground in front of the liquid-gold statue before it collapses.... the disintegrating dwarf statue would constitute a tsunami wave that would push stuff out of its way much more powerfully than a comparable water wave. It would not drown the dragon, but push it towards the opposite wall with incredible speed.
In a comment, the writer clarified that even though the movie doesn't incorrectly show Smaug sinking into the gold (at least, that's not the way it appears), even though the gold is in wave form, Smaug still shouldn't have been submerged:
...a wave of gold is to an animal like a water wave is to a piece of styrofoam or cork: that floats to the crest so easily that the wave doesn't have a chance to bury it underneath.
I'm not sure that this explanation makes sense or that the analogy applies. Granted, the movie scene probably isn't very accurate in terms of how liquid gold would behave (it does seem to crest and break much like a wave of water, and to move quite quickly), but I would expect that submersion would be a question of surface tension and pressure rather than density, and even though liquid gold does have a very high surface tension, a "wave" of molten gold doesn't seem like it should have enough surface tension to prevent Smaug from being submerged. I don't see how Smaug would be lifted by the wave unless it were coming up from below him somewhat. (Granted, the layout of the lair and the logistics of the scene don't seem to be entirely clear in the above video.)
So, the question is: how plausible is it that a very large (Smaug-sized) object or heat-resistant creature could be submerged by an even larger "wave" of molten gold?