Dear JML:
I think that there is a Swim with the Dolphins and small snorkel area at King's Wharf, however I'm not 100% positive. The Bermuda tourism dept. is pretty good about having tourism staff at the pier areas to give you info on places you may want to visit and they could verify this.
As for other snorkeling, I'm sure NCL will have a few snorkel trips to choose from for excursions. Have you read my "Back to the Beach" article on this section of CruiseMates.com? It suggests family friendly beaches in the Caribbean, Bahamas and Bermuda -- you may want to check it out.
Other ideas include the maritime museum and crafts market in the refurbished fortress in King's Wharf; the Botanical Gardens; the Crystal Caves guided tour; and the small aquarium/zoo with a small children's discovery room.
I hope this helps.
Smooth sailing,
Luisa Frey Gaynor
Family Cruise Editor