Can humans breathe in water as shown in the movie The Abyss? There are scenes in which a mouse is dropped in oxygenated (or some cool form of) water and it adapts to breathe. Is such breathing via some specialized water possible? Why or why not?

The scene with the rat breathing an oxygenated perfluorocarbon fluid was real. The rat was breathing a liquid, and some countries actually censored that scene due to perceived animal cruelty. This is real technology -- perfluorocarbons are routinely used today in liquid breathing ventilators for premature newborns with severely underdeveloped lungs. The liquid is much more effective at carrying oxygen than water. http://en.m.wikipedia.org/wiki/L...
However, the scene with the actor in the dive-suit was faked. Ed Harris held his breath during the scenes with the fluid-filled helmet. These fluids are very viscous compared to air, and are extremely difficult to breathe without mechanical assistance. Basically, you have to have a tube down your trachea and a circulation pump to force the fluid in and out of your lungs fast enough to provide the needed oxygenation and carbon dioxide removal. This is said to be deeply unpleasant for conscious people, and therefore is not in use on adults except for limited experiments. 
http://en.m.wikipedia.org/wiki/T...