Manjanggul Lava Tube is one of the longest lava tubes in the world (around 7.4 kilometres total), and a UNESCO World Natural Heritage feature in north-east Jeju where about 1 kilometre of the tube is open to visitors. Inside, the cave maintains a steady temperature year-round around 11–18°C, with lava stalagmites, stone bridges, and a 7.6-metre lava column — the world's largest known lava column — at the end of the public path. Bring a light jacket and grippy shoes; the floor is uneven and damp. A geological Jeju Island highlight for Muslim travellers, easily combined with Bijarim Forest and Hamdeok Beach. Modest entry fee, closed first Wednesday of each month.
