U.S. Navy does it that way in the full dunker. A couple rides visually, then the lovely swimming goggles that are blacked out. Done it personally numerous times. It's really no worse... except you have to have your procedures down and know where things are and what they feel like, and you must retain your reference point... and it can play with your head if you've never done it.
Even if you hit the water (heaven forbid) in broad daylight, you still may not be able to see due to lots of reasons. It is best to assume that your vision will be unusable to aid in your escape.
You are quite right that it's a good idea to do it blind for practice.
Last edited by Um... lifting...; 19th October 2008 at 05:22.