Imagine the benefits of being able to breath fluids.
Deep sea diving, being able to tolerate extreme G forces.
You did it when you were a baby. A mouse actually did it in the movie "The Abyss" (great movie btw).
Another useful application for breathing liquid is to cleanse the lungs.
Once inside the lungs, perflubron enables collapsed alveoli (air sacs) to open and permits a more efficient transport of oxygen and carbon dioxide. Test have been done on sheep, where their lungs were damaged, and pumped back to life.
So, maybe someday, you'll be able to spend a few days at the spa, getting Rolfed, mud facials, coffee enemas, and getting a nice warm lung bath.
LOL.