Passenger numbers for car ferry operations connecting the west coast city of Incheon and China have surpassed 500-thousand in the first half of the year.

According to the Incheon Port Authority on Monday, over 527-thousand passengers used ten car ferry lines traveling to and from China during the first six months this year for a monthly average of about 87-thousand.

The figure is up 69 percent from the same period last year and is close to an all-time high posted in 2011, when over one million passengers traveled on the vessels throughout the year.

Passenger numbers recorded 920-thousand in 2016 but then plunged to some 600-thousand in 2017 amid a Seoul-Beijing dispute over Korea's deployment of a U.S. missile defense system.

The number recovered to 810-thousand last year, when China appeared to ease a ban on group tours to South Korea.