They frequently ditch about ten miles short of Honolulu airport. Invariably, these low time pilots, none with sea training, survive without a scratch. During the air race season, I generally traverse the U.S. four to six times a year, coast to coast, in my Lance. I am far more nervous flying over most mainland terrain than I am flying over open ocean. Second only to a level farmer's field, water remains a top choice for an off-airport landing.
Few roadways are really safe.
Again, even at night, I prefer a water ditching to unknown terrain. With GPS, every pilot should know wind direction and velocity simply by glancing at the IAS and GPS groundspeed readings and turning accordingly until the differential is maximized. With the known elevation of the ocean and most inland bodies of water, the pilot has the opportunity to prepare for a flare in the last few seconds by keeping an eye on the altimeter. You are also quite incorrect when you state that it is difficult to estimate altitude over water. With several hundred hours of seaplane time in both lakes and open ocean, I speak from experience on this.