I would like to know the fastest,most convenient way to cross China from Vietnam (Halong bay) as i dont want to go back to Hanoi. if my cruise end at 3 or 4 pm, will i am be able to go to border (Mong Cai / Dongxing)? i want to go to Guangzhou as soon as possible.i i waste my night, i only have about 5 hours in Guangzhou. thanks for your help