Snorkeling at the Wall offered at dock?

I've looked at some of the Snorkel/Dive excursions offered that I can book online. I'd like to know if any of these are offered at the port if you haven't booked ahead of time? Grand Turk is our last stop and I don't know if the family will just want to kick back at the beach or do an excursion.

My concern is that the Conquest docks at 8am the same day, and the Magic (which I'll be on!!!!) doesn't dock until Noon. So Margaritaville and the beach at the port will likely be totally packed.

If there are people at the port offering a snorkel trip to the Wall, I can wait and see what we want to do while we're there.

Thanks for any help!

scroll down to the thread "White Sands". Lots of info there.I read the other day there is some one down the beach from Marguaritaville. There's also the dive shop in front of (behind) Jacks that will get you to the wall.