King of the cave ~ Postoina cave, shocking, 21 kilometers deep, can actually take a small train to visit. Stoina cave is located in the Republic of Slovenia, is the second largest cave in Europe. There are many scenic spots in the cave, and the cave is a spectacle. The cave is set with tunnels connected to it, forming a Qiwei cave promenade, with four main caves such as the brilliant hall, the slow hall, the crystal hall, the concert hall and so on. The temperature in the cave will be kept constant at 8-10 °C. Experienced guides throughout the journey, which took an hour and a half. There is also an automatic 15-language guided tour in the cave.