Breathing liquid is possible. Mice have been held under the surface in a beaker of liquid that is saturated with oxygen for several hours. This could allow divers to rise or sink rapidly without getting the bends. The only problem is the first breath – overcoming the instinctual fear of drowning. Doctors have used this technique to save premature babies, forcing them to breathe liquid when their lungs are too underdeveloped to breathe air.