I was on Water Island quite a number of years back....stayed at Sugarbird hotel (plus Honeymoon Beach was the beach the Kon Tiki Party boat went to). It was a nice beach with decent walk in snorkeling. Just watch out for the "grassy" part in the middle - baby jelly fish like to hide in there.
Not sure if anything there has been maintained though.
I'll be at Isle de Margarita the end of April (Golden Princess). I'm taking the Fiesta Party Bus tour offered by Princess. I have heard that there is a nice little beach/bar/shopping area not far from the pier.
Hope this all helps