You could breathe liquid, if it was the right liquid. Kind of mindblowing.
In order for any fluid to work for human respiration, it has to perform two main functions very well: delivering oxygen to the lungs and removing carbon dioxide. Air obviously does both quite well; so do some other combinations of gases (such as those used in diving). But it’s reasonable to think some liquids may be able to do the same thing
More here. Via AskMeFi.