Manjanggul Lava Tube

Manjanggul is the show cave of the Geomunoreum lava tube system, a tunnel left behind when the crust of a lava flow hardened while the molten rock inside drained away. About a kilometre is open to visitors, a wide, dark, rough-floored passage lit at intervals and dripping in places. The walls carry lines marking the levels the flow reached, and there are lava stalactites, rafts of fallen ceiling and a rock shaped like a turtle. The walk ends at a tall lava column formed where lava poured down from an upper tube. Bats live in the closed sections. The air stays cool all year, which is a considerable relief in August.

What you actually see

• The main passage - the wide, high tunnel with its hardened lava floor.
• The lava column - the tall pillar of stone at the end of the open section.
• The flow lines - the horizontal marks on the walls showing old lava levels.
• The turtle rock - the raft of solidified lava shaped like the island itself.

When to go

Any time of year, and especially useful on hot or wet days when the rest of the island is uncomfortable. Weekday mornings are quietest. The cave has closed for periods of survey and repair, so check that it is open before making the drive out, because there is little else at the site.

Honest expectations

It is cold, dim and wet underfoot, with an uneven lava floor that catches ankles, and photographs come out poorly without a tripod. There is no loop, so you walk back the way you came, which doubles the distance. Anyone expecting limestone formations will find it plain: this is one long grey tunnel, impressive for what it is rather than for decoration.

Nearby

Gimnyeong beach is a few minutes north and Seongsan Ilchulbong is half an hour east along the coast.