You can see most everything you will see on a regular dive by just snoreling Hol Chan / Shark & Ray Alley.
My whole family dives but on our last two trips we just snorkeled and didn't miss the diving at all. Traveling with dive gear is a real pain and trusting rental dive gear is unwise (personal opinion) so just go snorkleling, you'll have just as much fun.
Disclaimer: We have dove many times in many locations so maybe the novalty of diving is wearing off for us?????