We went early in the morning and there was amazing visibility. You could see ~30ft down to the reef with perfect visibility. There were immediately large schools of fish sleeping and swimming very close. There were a couple groups of turtles that the guides were following. This is a large group tour, so staying with the guide means being hit quite often and having to make sure you're not running into other snorkelers which was a bit annoying. I tried swimming a little bit away from the group to take a look at other parts of the reef and other fish but got yelled at to stay with the group. The group stayed looking at the turtles for ~30 minutes which got a bit boring. I wish I felt that I could venture a bit and look at other parts of the reef. It felt like a bit of a waste given the great visibility that day.
Overall, this is great for seeing turtles but I wish I would have chosen to go with a smaller group so I could feel a bit less limited.