Mahogany Bay has a very comprehensive website with a map. https://www.mahoganybaycc.com/
As far as snorkeling goes, Good is subjective to your past experiences. If you have been to West Bay, then it is doubtful Mahogany Bay would entertain you. But if you are new to snorkeling, perhaps it will. I have not done so, but that said, if you go to the end of the beach at the end of the dock, there is some sealife to witness there.
If you use the search here, you might find more information about snorkeling.