Black Friday: lifetime access is on a special offer in the app, until November 30. Black Friday: special offer on lifetime access, until November 30. Download
항해술은 바다에서 안전하게 항해하는 방법을 가르칩니다.hanghaesul-eun badaeseo anjeonhage hanghaehaneun bangbeob-eul galeuchimnida.Navigation teaches how to sail safely on the sea.