At Grand Case Beach Club, the best snorkeling from the beach is around the point the Sunset Cafe is on. Easy access into and out of the water from either side.
Happy Bay has very little snorkeling except to the right, facing the water, around the rock point.
You can get a boat to take you out to Creole Rock, just don't go ashore on Creole! Coral is coming back out there and there are turtles in the sea grass.
Hope this helps. <img src="http://www.traveltalkonline.com/forums/images/graemlins/Groovin.gif" alt="" />