manjaro
No-No Place-licky McNicky
found this intersting little bit somewhereon the net
'There have been several instances in the past where Hulk has not only spent extended periods of time underwater without breathing, but he has also moved his mouth and spoken beneath the waves. Until recently, this was unexplained.
However, in Incredible Hulk v3 #77 it is finally learned that the Hulk has the power to develop a gland that can create an oxygenated perfluorocarbon emulsion that filled Hulk's lungs, allows him to breathe and move his mouth as if he was speaking, even though his words are apparently still inaudible to the naked ear. It is possible this gland does not always develop during every transformation, since there are times when Hulk has been unable to breathe underwater.
Or, certain incarnations of the Hulk may not be aware of this gland and have not utilized it, presuming they could not breathe underwater. However, this is still mere speculation"