The feature film debut of writer and director Yoon Jong-seok, it stars Kim Kang-woo, Cho Jae-hyun and Park Si-yeon in the lead roles.

Marine Boy is the story of a former national swimmer who finds himself in debt, and out of desperation is employed as a mule by a gangster boss, smuggling drugs by sea.

[1] Former national swimmer Cheon-soo dreams of traveling to Palau, and to fund his trip he works as a swimming instructor by day while gambling at night.

During casting, he was keen to avoid stereotypes, and for the role of Kang wanted someone who looked more like a businessman than a typical gangster boss, choosing Cho Jae-hyun for that reason.

[2] Lead actor Kim Kang-woo had to overcome his fear of water and prepared for his role by undergoing three months of intensive training, which began with learning basic swimming strokes in a pool and progressed to more advanced skills such as scuba diving.