A national nature reserve with developed high-mountain karst, with characteristic rock formations and an abyss. Here we can find extremely rich calcareous flora. There are chains in some places to aid hikers. Hiking Route: Zuberec – Sivy Vrch – Return Start: Zuberec (734 m) Green trail: to Forest Lodge under Biela Skala (937 m) – [1:00 h] Red trail: to Biela Skala (1316 m) – [1:30 h] Continue to Sivý vrch (1805 m) – [1:30 h] Return via the same route – [3:30 h] Total duration: approx. 7 hours 30 minutes The path is closed from 1.11. to 15.6.