Visa required?

If you plan to stay in mainland China for less than 24 hours, it is not possible to do it without a visa. However, if you can allow to stay at least for a minute longer than 24 hours, in that case you can rely on a 240 hour visa free transit and no visa is needed. However, in that case you will do the following:

- You should take a ferry from Hong Kong to Nansha port (located south from Guangzhou and connected to it by metro) or to Shekou port in Shenzhen. These are two only ports that you can use as entry points into mainland China when entering from Hong Kong on 240 hour visa free transit, beside flying, of course.
- You will have to buy a ferry ticket from Shekou port to Macau even before your departure from Hong Kong because both Hong Kong and mainland China authorities will ask to see them as a proof of your transit. Departure time of the ferry from Shekou has to be at least a minute behind 24 hours after your arriving ferry arrival into mainland China. This is based on scheduled times.
- You will really have to take exactly that ferry you have bought your ticket for your travel from Shekou port to Macau.
- When you arrive in Macau, you can easily return back to Hong Kong by the first ferry from the same port.

I know that the above looks somewhat complicated, but it might be a solution for your travel plans. If you decide to proceed with your visit to Guangzhou, I wish you a nice journey.