SEOUL, South Korea (AP) — A ferry carrying 459 people, mostly high school students on an overnight trip to a tourist island, sank off South Korea's southern coast on Wednesday, leaving nearly 300 people missing despite a frantic, hours-long rescue by dozens of ships and helicopters. The high number of people unaccounted for — likely trapped in the ship or floating in the ocean — raised fears that the death toll could rise drastically, making it one of South Korea's biggest ferry disasters since 1993, when 292 people died. Some 160 coast guard and navy divers searched for survivors inside the ship's wreckage a few kilometers (miles) from Byeongpung Island, which is not far from the mainland. Lee Gyeong-og, a vice minister for South Korea's Public Administration and Security Ministry, said 30 crew members, 325 high school students, 15 school teachers and 89 non-student passengers were aboard the ship. Kang Byung-kyu, a government minister, said two of the dead were a female crew member and a male high school student. Yonhap news agency said the 146-meter (480-foot) -long ship, which travels twice a week between Incheon and Jeju, was built in Japan in 1994 and could carry a maximum of 921 people, 180 vehicles and 152 shipping containers. The water temperature in the area was about 12 degrees Celsius (54 Fahrenheit), cold enough to cause signs of hypothermia after about 1½ hours of exposure, according to an emergency official who spoke on condition of anonymity citing department rules.