My worst excursion I have to blame on myself - not the excursion.
Five years ago myself, wife and our 2 teenage children cruised on the Norwegian Wind and one port was at Roatan. We took an excursion to Tabanya Beach Resort for swimming, snorkeling and just general fun in the sun. My wife and I went to snorkel right away. My mistake was to not take one of the inflatable life jackets that they always have for snorkeling.
After being out for maybe a 1/2 hour we came to an area where the reef dropped from a depth of 5-7 feet to maybe 20 feet. I'm a very poor swimmer, so the sudden depth under me rattled me a bit and I turned around to head for shallower water where I knew it would be safer for me. I immediately discovered that a slight rip current had been developing, but I hadn't noticed as I had been swimming out with the current. Now I was facing the current and knew that I was in big trouble because of my being a very weak swimmer and not having a floatation device.
I worked very hard to keep from going into a panic and also looked for help. We had ended up being on the fringe of the snorkelers and there was nobody within 50-60' of me. I noticed one person who appeared to possibly be my wife (hard to tell with goggles and all the stuff on...lol) so I made a frantic wave and fortunately she caught on that I was in trouble and immediately came over and assisted me to shallow water. Without her help I doubt I'd have made it.
I still snorkel but, needless to say, WITH a floatation device and with much more caution. I didn't pay close enough attention - I do now.