I'm an Australian visiting China, I want to make a trip for a day or two to Hong Kong while I am in Shenzen. I would return to Shenzen afterwards.
It seems I need a double-entry visa for this, but one condition of the double-entry visa is that you must prove incoming/outgoing flights/trains from China.
The problem is that I can't seem to find anywhere online to book the train from Shenzen to Hong Kong. It seems that it is just the regular metro. Should I look at booking a bus or something? A ferry was mentioned elsewhere but I can't find booking for that either.