Which of these ports would be best for Snorkeling: Labadee, Puerto Plata, St. Thomas, or St. Maarten?

[WingerSupreme]

Doing an 8-night Celebrity cruise in December, and my wife really wants to go snorkeling, so that's one excursion we're definitely going to book. The four ports are Labadee, Taino Bay (Puerto Plata), St. Thomas (Charlotte Amalie) and St. Maarten (Philisburg). Any recommendations as to which would be the best (or worst) place to snorkel, or any specific recommendations on excursions? Thank you!

[lil93bit]

Coki Beach is a great place to snorkel on St. Thomas. If you have your own gear, I would not pay for an excursion as it is a perfect beach entry.  It has been several years since I went, but we actually did a shore dive there and just rented tanks. (We took a taxi - I think it was - to get there). 

I tried to find somewhere at Labadee to snorkel, but there wasn't anything there to dive or snorkel.

I think I found a scuba shop at St. Maarten, but I don't remember. Good Luck.