Can I just get a single entry visa for china

I am doing a cruise the itinerary in china as follows: Hong Kong 1day Xiamen 1 day 1 day at sea shanghai 1 day. 1 further day at sea and then 2 days Beijing nd then to Korea. As far as I can see all Chinese ports one after the other interspersed. With 2 seas days therefore I presume we do not leave China and re-enter. Can anyone advise?