We did the 9:30am excursion and saw many turtles! The staff on the boat were really friendly and professional. The boat trip to the snorkel spot is not super long, allowing plenty of time to snorkel. Staff gave great overview of snorkel gear (mask, fins, vests (which could be inflated)) and instructions for best opportunities to see turtles. The tour group is kept in a fairly small area, which can get a little crowded with everyone trying to see the turtles. There were also a few other snorkel boats in the area but they did not interfere with our turtle viewing. Water, soda, and snacks were provided on the boat.
This is not a critique of the tour, but a general note that the snorkel spot is out from the shore and the swells were a little high. Strong swimmers will have no issues and one of our party, who does not consider herself a strong swimmer, was fine after she inflated her vest (and had a great time!). There were several children on our tour who also seemed fine in the water. If you are accustomed to snorkeling in the Caribbean or very shallow water though, just be aware that the water is a little rougher in this area.