How can they be water passengers? What are the conditions? Why can they travel freely between Hong Kong and the Mainland? Most of the water passengers are from there, so they are in a hurry.

There are more water passengers than Hong Kong itself, you know, because Hong Kong residents can travel to and from the mainland freely. Now some mainlanders have joined in. I estimate (or affirm) that they hold a business pass, and there is no limit to the number of trips between the mainland and Hong Kong within the validity period of the endorsement, so they can also run at both ends. However, port supervision in Hong Kong is also very strict. Once it is found that people with business endorsements are selling dog meat, they are not allowed to enter Hong Kong again.