I found somewhat of a description by doing a search on google, but it doesnt sound very ideal to me (Im a scuba instructor but havent taught in several years). Of course I havent seen anything like this so it may work. Id love to hear from someone who has done it .
You would be given a underwater scooter that you can use to skim along the surface. I think this might be a problem as if you go too fast, water will come spilling into your snorkel. Nothing like inhaling salt water! It can take you down to 3-20 ft for a closer look at the coral. This worries me as I can just see people crashing into the coral unable to control the scooters, or going deeper than 20 ft. Its bad enough to see novice snorkelers standing, kicking or touching the coral, but to crash into it? OUCH! There goes a few hundred years of Mother Natures work! And keep in mind, youre doing this while holding your breath-not wearing a tank full of air, so if you go down deeper than you can manage, you may run into trouble. Theres also the issue of pressure buildup in your ears if you dive down too far.
Personally Ive never really gotten into snorkeling. When I have done it (and while scuba diving) I prefer to go slow, and often stop/float. I find that the fish arent scared away as much by doing this. If youre able to, try scuba. I find it so much more relaxing and rewarding. You can get close up to the reef, swim through wrecks, see a lot more than you would snorkeling, etc. I used to think you had to go fast to see it all, until I took up underwater photography. Boy did that open a new world for me-the really small stuff in the coral is so interesting.