Question about 144 visa free travel

So you plan to go to Shenzhen from HK and then back to HK? It's not an eligible route for 144-hour visa free transit. But you can try to obtain a visa on arrival at the border between HK and Shenzhen, like at Luohu or Shekou.

No, unfortunately, this is not possible. The only way is to apply for 5 days visa on arrival at one of eligible border crossings. If you decide to do that, I suggest you to take the first morning ferry from Hong Kong to Shekou port in Shenzhen and to obtain a visa on arrival there. The reason is, this is by far the least congested visa office of all. So, this is a solution, but you should be aware that the price for such a visa is 956 CNY and can be payed only in cashless form i.e. by card. Please, have in mind that this visa is limited to Shenzhen administrative borders and you cannot leave the city. After your stay in Shenzhen, you can return to Hong Kong using any border crossing as well any mean of transport as you wish, high speed train included.

So, if you decide to take a ferry, it is operated by CKS -Chu Kong Passenger transport company from Hong Kong - Macau Ferry Terminal at 09:00 in the morning.