Tarasas Sereda
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Interesting place of another world. 100% worth to visit if you have not been to such places. It takes around 1 hour, you explore 600m of cave out of 2.5 km discovered.
Important to know that even though oficially they present just few entering time, in reality excursions are taking place every 15min. So worth to come any time and wait. Last is around 15h.