I apologize, and certainly didn't mean to alarm anyone. I didn't describe this very clearly.
A "norte" is simply a cold front bringing in heavier winds from the north. Sometimes they bring rain, sometimes they don't. Sometimes they blow through in a day, and sometimes they last for a few days. However, certainl no reason to cancel a trip, because you truly never know. Furthermore, depending on wwho you are diving with, you may still get out to dive. If the port is open for the larger boats, I secure spaces on a larger boat for my customers and my divemasters. My customers then have the option of diving or waiting for it to pass.
The weather today is actually gorgeous, it is just very windy and much cooler than a normal Cozumel day. It's great if you live here, but not so great for divers who want to dive.
The "port" refers to the channel and the diving/snorkeling/boating/fishing areas in general. To correct Don, the port closure in these regards has nothing to do with the cruise ships or the cruise ships hitting the reefs.
The harbor master makes the call to close the port to recreational activities based on the winds and wave height and whether he deems it safe for boating. The diving itself is not affected so much, as are the boating and surface conditions...therefore, making it unsafe to take people out diving or snorkeling. Tourism is the core of the economy here and the harbor master makes the call with the intention of keeping everyone safe. It is also dangerous and difficult to dock the boats and get customers on and off the boats at the piers as well as in and out of the water.
Sometimes the port is closed to small boats only, other times it is closed to all boats for recreational purposes. When the harbor master makes his report, he indicates what size boats can go out (ie: boats over 40 ft only is the usual). If the port is closed and boats are caught taking customers out, the fines are very high and in serious cases, certain permits can even be revoked.
I hope this clears things up a little. Sorry for the skimpy information the first time around