Hi, Single or Multiple Visa

Your advice is needed about type of visa required.
We arrive in Shanghai by air Wednesday May 2 2018 to board cruise Ship Seabourn Sojourn on Thursday May 3 2018.
The ship is calling at three other ports( Yantai,Tianjin,and Dalian) before crushing to South Korea and Japan.
Given that we are going to these four ports without visiting another country in between I need to know if only a single entry is required or a multiple entry.
Have used your services before and will book port tours with you where we can.
Many thanks
Peter Fox