This movie is based on a true story called "the 7th Taechangho accident" that happened at South Korea, in 2001. A group of illegal immigrants from mainland China was tried to smuggled to Korea but 25 people were suffocated to death in the fish tank and dumped to the sea by the fisherman. Rest 35 people were set on foot to Korea and they disappeared until one was found, arrested and confess the whole event to authority.
Sea Fog (2014) is the first feature film directed by Sung-bo Shim, who co-wrote the screenplay of Memories of Murder (2003) with director Bong Joon Ho. Bong is this film's producer.
Official submission of South Korea to the best foreign language film category of the 87th Academy Awards 2015.
Kim Yoon-seok was first cast in the role of the ship's captain in June 2013. Song Joong-ki was originally offered to star opposite Kim, but had to turn down the role when he received his enlistment papers for mandatory military service. K-pop singer and actor Park Yoo-chun was cast instead in August 2013, in his big screen debut.
Filming began on October 6, 2013, with locations in Masan, Goyang, Busan and Ulsan, and ended on March 6, 2014.