One needs to wear scuba diving suits that are designated for this activity to enjoy this adventure watersport. The diving suits are designed to keep you warm underwater. You can choose 5mm thick scuba diving suit and hood in winter when the water temperature dips to about 25 degrees Celsius.
However, if you feel the water to be still cold, you can wear long scuba diving suits just to be double sure. During the summer months, the waters of Hong Kong are at about 30 - 32 degrees Celsius and 3 mm scuba diving suits will be fine.