Police said that Kang Min-gyu, 52, had been missing since Thursday and appeared to have hung himself with his belt from a tree outside the gym.
Out of 475 passengers and crew on the ship, about 340 were students and teachers from the Danwon High School in Ansan, an industrial town near Seoul, who were on an outing to the resort island of Jeju.
They account for about 250 of those missing. REUTERS To watch Nicole Hajal's report, please click on the video above.