Happy Bay is nice. Last time we went we came across sea turtles among-st the rocks...we startled each other. The new masks are becoming quite popular. I have seen people loving them and others struggling. I probably still prefer my Scuba mask and a quality snorkel with a dry top. (Easy to adjust position). I don't scuba any more and don't use full on fins. Instead my wife and I bought short swim fins. Easy to pack & light and they do the trick in light/calm conditions.
We stay at Simpson Bay resort for our visits, and believe it or not we find some of the best snorkeling right off their small beach (shared with Flamingo). You have to swim out about 100 yards, but you will be rewarded. Use the point to the left of the beach as your starting point and swim straight out. (if the yellow or red surf flags are out...the current will work against you so use caution.) Otherwise on a calm day its great. Also if you swim just off the swim buoy line (Ocean side) You may be rewarded with a big ball of bait fish. If you hang around the ball long enough you will most likely see a barracuda or 2 lurking at the bottom of the ball.