Originally Posted by
GSM763
There's a fairly long border control process (the queue stretched for about half a km when I was in Hong Kong) that you'd want to leave plenty of time for. However, you can get a ferry to the mainland from Hong Kong airport without entering Hong Kong via the SkyPier.
Indeed and to state the obvious, to use the high speed train route you have to clear Hong Kong immigration twice.
There's also a transfer from HKIA to Kowloon allowing time for the connection.
I've done it on the old train in about 5 hours so I guess you could do it on the new one in about 4.
Not dissimilar to landing in Newcastle to get to London.
Of course the airfare to HKG would probably be rather higher, so you would likely be paying a pretty penny to insert a fairly complex additional transit.
Not great for people who would want to save money, people with small children, people with lots of luggage, people in a hurry or those wanting to maximise predictability.