Thousands of fireflies illuminate the darkened forest experience zone during Everland’s Midsummer Night Firefly Festival in Yongin, Gyeonggi Province, Thursday. Courtesy of Samsung C&T Resort Group

YONGIN, Gyeonggi Province — Step out of the scorching heat and into the twilight air, where a dim, canvas-draped shelter marks the gateway to one of summer’s most magical spectacles.

Here, visitors pause to learn the fragile secret of the firefly: a creature that spends an entire year preparing for just about 10 fleeting days of illuminated adulthood.

Descend the basement steps, and the world transforms. You emerge into an exhibition hall shrouded in shadow, softly pulsing with thousands of tiny, living embers. It feels like stepping into a bioluminescent fantasy forest.

"Fireflies carry tiny lanterns on their abdomens — one light organ for females, two for males," explains Kim Jin-mok, a dedicated zookeeper who oversees the sanctuary.