Gyokusendō, Limestone cave in Okinawa World, Japan

Gyokusendō is the show cave of the Yuhi River cave system in Nanjō, Okinawa. Its public route runs about 800 metres, from an entrance at 14.4 metres above sea level down to an exit at 4.7 metres. The cave lies 30 metres above an underground stream that enters from the Yuhi River upstream and rejoins it downstream.

In March 1967, a survey by Ehime University's academic exploration club first revealed the full extent of Gyokusendō. The cave opened to tourists on 28 April 1972 as part of Okinawa World, operated by the Nanto company. In 1971, surveys by Kashima and Yamauchi led to the cave system being renamed the Yuhi River underground cave system.

The cave lies within Okinawa World, a theme park that also holds the Kingdom of Ryukyu dance shows and craft workshops. Near the old entrance tunnel, jars of awamori are stored in the cave's constant temperature, a use visitors can see.

The cave is open daily and the walkways are equipped with railings and lighting for safe passage. Visitors should know that it stays cool inside, so comfortable walking shoes are recommended.

The cave's old entrance tunnel, a stepped passage, is now used to store jars of kūsu, Okinawan aged awamori, because the cave holds a constant temperature. The cave also shelters the Okinawan horseshoe bat, the giant mottled eel and the Kuroiwa's ground gecko.