O.K. my two cents worth again. I agree with Phil. When there is an outgoing current at Hol Chan it is simply a Rip Tide. The higher the tide and stronger the winds generally mean a stronger outgoing current in the channel during out going tides. All the water that comes over the reef is trying to find it's way back out through the channels. This is not all that easy to predict. For some reason this not widely understood by a lot of the guides. The tides published are for Belize City. I believe San Pedro is about 50 minutes earlier. There are many factors that can effect the strength of the current - such as large ocean current and upcoming weather changes. Generally the ocean reacts faster that the air does to weather changes. This is why some type of mechanical current indicator would be great - it's hard to know what's happening without technical information. I guess the rangers could "dive in" every hour to check conditions but I don't see this happening There are plenty of areas in the park that can be snorkeled without entering the "danger zone". If there were zones of safety indicated and enforced then the park would very seldom need to close to snorkelers.
I also believe that times have changed and now all snorkelers should be required to wear a snorkeling vest. At least if they need it they can blow it up and be safe - if they don't need it, then keep it deflated and it's not encumbering. Times are changing and the tour operators must change with them. It only takes a few incidents like this for the safety reputation of an area get internationally tarnished. Belize can not afford this to happen.
Sorry for running on for so long but this was a horrible incident that should never have happened - simple as that. It's time to put rules in place to keep it from reoccurring.