Meh... If you want snorkleing but with immersion... then get one of these....
They're usually tethered to a float to about 15-20 ft so A) You can't get compressed and B) The dive master can track you. They probably cost about 1/20th the price of that 'boat'.
I like these things though. Last time I was SCUBA diving off the Bahamas, I would sneak up on these things, and suddenly tap on the window, people would freak out.
And since I'm on a roll, here's some photo's from that dive trip, doing some of the Shark dives. (Stupid airport gate security refused to hand check the film bag, so the scanner DESTROYED most of the film, this is all I got form that dive

)
EDIT:
Found a VERY short clip of the Dive from one of my dive partners. I just emailed her to see if she had more of the footage.
http://img88.imageshack.us/i/no8.mp4/
Ok since that link is BS, I went through the hell that is signing up for youtube, so here is the VERY short video: