'Zeleni vir' (Green spring) is as strong source located at the bottom of a cave at the foot of a high and colorful cliff along which falls the stream and sprinkles the cave’s entrance with water drops. The source was named after the emerald-green water of the small lake whose source in the cave cannot be seen. The waters of the lake, through a small dam, enter into an underground channel that brings the water up to the water power-plant built in 1921, which is the first water power-plant built in this part of Croatia. The area around 'Zeleni vir' was were proclaimed special geo-morphological reserve in 1962. The reserve is located in the area of the municipality of Skrad, at 302m-649m above sea level. The reserve can be reached on foot along climbers’ trails or by car via a paved road.