Yup sure have. It's in Shark Reef and you'll pick up a snorkel and mask at the entrance then go to a step where you'll enter and swin through a reef with lots of fish and small sharks. We enjoyed it.
It's wonderful! And not scary if you have younger ones. Just don't try to look behind you! You'll end up with a snorkle full of water (like I did) The gear is sanitized, instructors fill you in before you take the plunge and they have life guards right there in the water with you. There is a gentle current that 'encourages' you along to keep things flowing. We did this time and time again! Don't forget the underwater camera!
I word of advice, be prepared the water is FREEZING!! But they have to keep it that way for all of the marine life. I absolutely loved this attraction!!! To some it may be difficult breathing through the snorkle but it is definitely a must do! Hope you have a wonderfully magical trip!!