Just as biking all downhill isn't really training, neither is snorkeling off the beach. But what a cool experience! I grew up in Corpus Christi, so snorkeling wasn't exactly something we did. Even if the water were at all clear, which it usually wasn't, there simply wasn't much to see.
By contrast, just off the beach at Kaanapali, there were beautiful reefs, abundant and varied species of fish, and sea turtles. I couldn't believe the turtles, so docile and comfortable with a bunch of people swimming around them. My brother-in-law even held onto one's shoulders and went for a ride (which we found out is illegal. . . .).
These pictures, taken with one of those disposable underwater cameras, aren't great, but I hope you enjoy them. I know I enjoyed taking them! Aloha!