Boat dive!i racked up about 35 dives so far mostly north east coast between Long dong bay, bat cave, and secret garden, with 2 boat dives .i think season would be closed soon the viz was very bad lost my buddy on my last dive. was taking photo vis was less then 5 meter with lights on if u can belive it. right now im planning to go back to thailand to dive or phillipines idk yet...
Which operator? I am interested but for next yr.
Oct is a bit late in Republic of China(Taiwan).
There are many places in Philippines but you have to be careful this time of the year ie. typhoon. But I am going to Puerto Galera next weekend nevertheless because flight from HK to MNL is dirt cheap(C$100.00 for round trip fare but hand carry only).

Hong Kong issues T3 as Severe Tropical Storm Matmo edges closer
Hong Kong’s weather will be cloudy with a few squally showers and thunderstorms later in the day, forecaster says.

This typhoon won't affect HK or Taiwan as it is moving westward. But my return flight from Taichung to HK was delayed by a day around same time last year.

Typhoon Krathon: two people killed and two missing in Taiwan
More than 100 injured as schools, offices and financial markets shut for a second day

Thousands evacuate as Super Typhoon Kong-rey makes landfall in Taiwan
Super Typhoon Kong-rey made landfall in Taiwan on Thursday as one of the most powerful storms to hit the island in years.

All the Marine Parks on the West coast of Thailand usually open around 15th Oct.
LoB to Similan is good but I won't recommend it at the beginning of the season. However I am going to Koh Lanta and Koh Lipe from 07th Nov onward for two weeks.
Enjoy the National Day holiday(10th Oct, Double Ten) in Taiwan.