Korallgrottan Travel Guide

Nestled in the rugged Frostviken region of northern Jämtland, Korallgrottan stands as Sweden's longest cave, with more than six kilometers of mapped passages weaving through marble bedrock. Formed over millennia by water seeping through limestone fractures, the cave exemplifies a classic karst landscape—Sweden's most distinctive—where dissolution has sculpted tunnels, potholes, and expansive halls. Surrounded by the 26 km² Korallgrottan Nature Reserve, established in 1994 and part of Natura 2000, the site protects this unique geology alongside neighboring Bjurälven reserve.

Unveiled to the world in 1985 by speleologists, Korallgrottan surpassed Gotland's Lummelundagrottan in length by 1999 after years of meticulous mapping. Four entrances—Klyftgrottan, Skymningsgrottan, Isingången, and Doliningången—lead into a labyrinth secured by an iron gate, accessible only via guided tours. The cave's marble bands create mesmerizing wall patterns, while erosional features like scallops and potholes reveal the slow artistry of subterranean water.

The cave's name derives from its abundance of small, white stalactites resembling marine corals—knobby, bulbous speleothems no taller than 10 cm despite 8,000 years of growth since the last Ice Age. These delicate dripstones, growing at a glacial 1 cm per millennium, cluster in abundance, their stark whiteness contrasting the dark marble. A waterfall graces one entrance, known locally as Grottan med vattenfall, adding a dynamic auditory element to the still chambers.

Above ground, the calcium-rich soil fosters lush vegetation rare in this high-latitude setting. Eastern slopes support dense forests, while western areas transition to mountain birch and open fell. Storliden's east-facing incline harbors an ancient, primeval-like woodland, teeming with diverse flora that thrives on the karst's mineral bounty. This biodiversity complements the underground spectacle, forming a holistic natural haven.

Exploration requires full caving gear and local guides, navigating crawls, climbs, and chambers at a constant 4°C. Tours, available midsummer through August on select days, cater to those over 10 years old, emphasizing the cave's wild nature—no lighting, no handrails. The vertical range spans 124.5 meters, blending physical challenge with profound isolation in Sweden's subterranean frontier.

Situated between Stora Blåsjön and Leipikvattnet along Vildmarksvägen, Korallgrottan anchors a remote frontier near the Norwegian border. The area's fjäll terrain invites hikes to viewpoints like Halvvägestklumpen, offering panoramas of lakes and peaks, while underscoring the cave's role in a broader tapestry of untamed Jämtland landscapes.