Bangseonmun Gyegok is a valley in Jeju that connects the area between Sinjeju and Gujeju to Halla Library along the Ara Dulle-gil. A deep valley formed where the roof of a lava tube collapsed, it holds a natural bridge formation and a turtle-shaped rock, with forest and oddly shaped stones running through it. The path from Halla Library to Bangseonmun is used by residents as a morning exercise route, and it is dangerous when it rains. Access to the valley is currently closed due to the risk of falling rocks, so it can only be viewed from the walking trail above.