My husband and I are going on a cruise in September, and neither of us have ever snorkeled, but we want to try it for the first time. Here are our options:
Buck Island (St. John)
Trunk Bay (St. John)
Creole Rock (St. Martin)

Let me know what you think would be our best choice. We definitely want to see a lot of different species, coral, etc. Also keep in mind that my husband is not a super strong swimmer. Thanks!!!

I think you mean Buck Island, St. Croix? If so, I've heard lots of good things about the snorkeling there. Maybe you will get a response from someone who has been there lately.

In all fairness, St Martin is NOT renowned for snorkeling, though Creole Rock IS nice, but not anything fantastic.

Trunk Bay (St. John) and Buck Island (St. Croix) are both much, much better for snorkeling than Creole Rock (St. Martin).

FYI - Buck Island is part of the St. John National Park but it is much closer to St. Croix than it is to St. John which my be one of the reasons OP is a bit confused as to it's location.

I agree St. Martin is rated poor, not even "fair" for snorkeling. Trunk Bay abnd a few others on St. John are your best bet of the 3 locations.

We port in St. Thomas, and they have Buck Island under St. John. Must be because of the National Park thing.
So, it sounds like Creole Rock is out. What sounds better - Trunk Bay or Buck Island???

I'm going to take a boat to Buck Island while in St. Croix in May, but I snorkeled Trunk Bay in St. John a couple years ago and liked it a lot. Everyone talks about the underwater trail there which is kind of cool but a little over-hyped in my opinion. It is a good beginner spot and also has a nice beach. I think Trunk Bay would be a lot closer than going down to Buck Island, and hopefully you'll also get to check out St. John and walk around Cruz Bay since it's a cute town.

I have yet to find any good snorkeling around St. Martin. I haven't snorkeled Buck Island but I have Trunk Bay. It's a good snorkeling spot. It's pretty close to the shore so you don't need to swim a long distance. No worries about not being a strong swimmer. You float better in salt water plus life vests or belts should be available for those who feel more comfortable with one. You don't need to put the life vest on. I've seen many people kind of swim on top of it, holding it around their middle. That seems to work well and give some peace of mind.

We had great success snorkeling right off the beach at Caneel Bay on St. John. I think one of their beaches is open to the public and that's where we saw an octopus, an eel and sea turtles. It was great. There's also great snorkeling off of Scott Beach at Caneel but I'm pretty sure you need to be staying at Caneel Bay in order to access Scott Beach. At least that's how it was when we were staying there a few years ago.

ok there seems to be some buck island confusion. there are 2 of them. the one everyone above is referring to is very close to st. croix and not where your excursion will take you. there is another buck island just off the south side of st. thomas in what is called the Buck Island National Wildlife Refuge. it is not part of the national park on st. john.
i have not been but fodorite Dianebridles has. she took a 1/2 day excursion. if you copy/paste her name to the search box you'll find a bit more of what she had to say in various threads including her trip report.
buck island vs st. john: buck island is closer, has no island services (i assume your excursion includes food/bev) & will be much less crowded.
as you've never snorkeled a guide would be most useful. they know where to look for fish/coral. i'm not a super swimmer either but snorkeling is my fav sport these days. i use a vest like this one: http://www.leisurepro.com/Prod/RFTSV...3don%26Hit%3d1
the only time i use it (ie blow 2-3 breathes into the tube) is when i want to tread water to adjust fins or mask, as the salt water really does make you floaty. to snorkel easily do not use your arms other than to alter direction - use fins trying to move from hips rather than knees. swim slowly - you'll see more stuff. make sure you're mask is tight to your face - a single strand of hair will draw in water. if your snorkel starts to sound a smidge bubbly you've gotten a little water in - to clear blow out a strong puff of air.
and fyi please please don't touch any corals with hands or fins - it kills them.

thanks everyone. and yes, virginia, i found out that the buck island off of st. john is basically just a tourist spot, and the snorkeling is not good at all. it sounds like we will most likely snorkel at trunk bay.
i greatly appreciate all of your feedback!