Turtle Cove Child Question

[LizzieandLuke]

I am planning my first family cruise in August 2014. I would like to do the turtle cove snorkel cruise at St. Thomas. It seems very calm and family oriented. My daughter is 11, on the swim team and has no fear. My son 9 is special needs and afraid of everything and cannot really swim. He does great in the pool with a floatation vest and loves the beach and my husband and I would always be by his side. I guess my question is does the ship anchor at sea and everyone goes into the ocean or does it ever dock on the beach. If he was afraid to get off the boat would it be a problem for my husband and I to take turns staying with him while the other swam with my daughter. I always like to give him the opportunity to try new things and my daughter is really looking forward to swimming with the turtles so I don't just want to go to the beach and snorkel from there. Any help would be greatly appreciated.