The articles mention that the group involved was "on holiday", so it is possible they were unfamiliar with the area in which they chose to dive. We don't know if they entered the water over the rocks and intended to exit there, or were forced to attempt exit there by currents. We don't know if the seas changed between the time of their entry and the attempted exit. Even without knowing those answers, it's easy to take the lesson of knowing your dive site and planning your exit before you enter.
H2O 70, I got from the articles that the fatality was one of the rescuers who fell onto a rock and that both divers are okay. I don't see where anyone else is either critical or missing at this point, either. Whether they were scuba or snorkelers is still cloudy to me. Snorkel makes more sense combined with the rest of the story, but I wouldn't put money down on either side based upon those articles.