However, it's not all bad news and it certainly isn't illegal (as somebody mentioned) for Liveaboard Operators to take customers out to the Similan Islands before the 1st November! If this were true, then the PADI 5 Star Dive Centres of Khao Lak would not be running liveaboard trips out there - would they?! I know of at least three highly reputable Khao Lak Liveaboard Operators who have 4 days/4 nights trips departing on the 15/10/11 and the 18/10/11.....
As a matter of fact, yes, it is illegal to take people into the park when it's closed for the season. There is a lot that goes on "under the table" when operators violate the park closure regulations. The fact that a dive center has paid PADI a hefty fee to sign up as a 5-star diving center does not guarantee that it follows the letter of the law.
Having said that, there are a few operators who do "get permission" (guess how?) to start trips in October. Sometimes those trips even go out, and at other times they are canceled for lack of minimum passenger numbers for the trip to be profitable. Sometimes (but less often) weather concerns come into play and cause cancellations.
For somebody who is traveling halfway around the world and wants to make fairly certain that their trip will go as planned, coming in October for a liveaboard trip introduces significant uncertainty. For backpackers and others who don't have fixed itineraries or tight travel dates, it's less problematic.
Believe me, I am in the business of selling these trips, and I definitely want to make sure my customers are not disappointed so that they will come back to me in the future and tell their friends, too. If I believed that selling trips to the Similans in October was likely to produce
satisfied customers, I would definitely not be discouraging people from buying these trips! However, I value my professional integrity, and I feel it's important to be honest. My honest advice is that unless there's no alternative, don't plan on coming for a liveaboard trip to the Similans in October. There's a fair chance you'll be disappointed in one way or another. If there's no other option, let's try, and we'll cross our fingers for good luck!