There is a ferry called East Pearl from Inchon,South Korea -Dandong, China 3 times a week(Mon, Wed, Fri). It will take 16 hours.
From Dandong- Inchon 4 times a week.(Sun, Tue,Thu, Sat).
You can join in the tour to North Korea from Dandong- Pyongyang by train.
The following is the time table of the East Pearl Ferry.
For more detail please visit our tour FROM SOUTH KOREA- NORTH KOREA