A hand-dug tunnel under Cijin Island's southern hill, originally an air-raid shelter from the Japanese colonial era. The Kaohsiung government reopened it in the 2010s as a public art installation — its tiled passage is now lit with shifting pastel neons, and the side rooms hold rotating sound and projection works.
Best at dusk when the natural light at the entrance complements the artificial light inside. The tunnel exits onto a viewpoint over the Taiwan Strait, with the Cijin Lighthouse on the hill above. Free to enter. Reach it by following the southern road from the Cijin ferry pier for about fifteen minutes, or hire a bicycle.