A signboard at Ryusendo cave's entrance says, “Reopens from March 19, 2017.” Visitors admire the blue surface of an underground lake in the cave, which is illuminated with light-emitting diodes (LED), in Iwaizumi, Iwate Prefecture, on March 15. (Video taken by Tetsuro Takehana)

IWAIZUMI, Iwate Prefecture--Back to looking its best, the Ryusendo cave here has regained its mystical blue color after Typhoon No. 10 wreaked havoc last August and will reopen to the public from March 19.

Local residents and volunteers were treated to a special preview of the famously clear waters on March 15, which had been turned dull and murky by the typhoon.

“It is a relief to see the mystical blue come back,” said local resident Taiko Kumagai, 72, looking at the blue surface of one of the underground lakes illuminated with light-emitting diodes (LED).

Ryusendo is a popular sightseeing spot known as one of Japan's three greatest limestone caves and a government-designated natural treasure.

Heavy rain flooded the underground lakes, one of which is 98 meters deep. The pathways, distribution boards and other features of the cave were damaged after being inundated due to the natural disaster.

The facility and its infrastructure have undergone repairs for the past six months, resulting in the opaque water becoming crystal-clear once again.