A North Korean man has crossed the heavily guarded maritime border into South Korea, local media reported on Thursday. The man had crossed the mouth of the Han River in the west of the Korean peninsula and finally reached the South Korean island of Gyodong, the South Korean news agency Yonhap reported, citing military circles. The circumstances are now being investigated by officials from the Ministry of Defence, it said. Many North Koreans leave their impoverished and authoritarian country every year in search of a better life, but attempts to escape by sea are rare. Most people wishing to es…