Mesačný tieň — 'Moon Shadow' — is one of Slovakia's most remarkable underground worlds, hidden beneath the Horvátov vrch massif in the High Tatras. With over 32 kilometres of mapped passages and a depth of 451 metres, it ranks as the second longest and third deepest cave in the country. Discovered as recently as 2004, it continues to grow with every expedition.

This is not your typical tourist cave — Mesačný tieň is a raw, living system still being explored by cavers year after year. Every season, speleologists push further, uncovering 2–3 kilometres of new passages. Above ground, the High Tatras landscape surrounding the massif is breathtaking in every season — dramatic ridgelines, dense forests, and crisp mountain air that makes even the approach feel like an adventure.

• The cave is located within the Horvátov vrch massif in the High Tatras, Slovakia. Access to the cave entrance is restricted and not open to general visitors — the surrounding area is accessible via standard High Tatras hiking trails.

• The cave is not open to the public — entry is permitted only for authorised speleologists with proper permits.
• Cavers are actively searching for an alternative entrance that could eventually allow guided public tours.
• The site lies within the Tatra National Park — all nature protection regulations apply.

Discovered on 26 June 2004, Mesačný tieň is already the second longest cave in Slovakia, surpassed only by the Demänovský cave system (41 km). Its story is far from over — every new expedition rewrites its record.