I've snorkeled in Belize, Roatan, Cayman Islands and Hawaii, and this was my first time in the Keys. I have to be honest, this was the most difficult conditions for snorkeling in terms of choppy water. My kids who had no trouble at all 2 years ago in Roatan when they were younger were hanging onto the anchor rope for dear life and never got to see anything. Depending on the sea conditions (is it worse in winter?) I would not advise this tour for anyone under 14 or anyone who is not an able swimmer.
Getting back onto the boat was a challenge even for the adults as the waves were tossing people into the stairs. And the little amount of time actually in the water was a disappointment. I saw some yellow snapper and a barracuda and that was it. It took a long time to get there, a long time to go through safety talks, and a long time to get everyone off the boat. In the end I probably had less than 20 minutes in the water.
The boat was crowded and the snorkeling area was packed with people running into each other. While the open bar is nice I would have done a different tour if I had known more in advance.