This accumulation lake is 3 km away from Ogulin and the Hotel Frankopan. Because of its beauty and size (with its 170 hectares it is the eleventh biggest lake in Croatia) is called the Ogulin Sea. The lake is a favourite picnic spot for rowing, windsurfing, swimming, diving, but also a meeting place for fishermen. A surrounding area is an excellent place for pleasant walks and cycling.

The lake is located on the River Dobra shortly before the river sinks into Đula's abyss. A dam was built on the river somewhere about one kilometre away from the centre of Ogulin and the Hotel Frankopan and that is how the artificial Lake Bukovnik was created. From the lake, water is drained through 30 kilometres long canals to the hydroelectric power plant Gojak.

Forest or Green Lake is located in the village Ivanac on the slopes of Velika Kapela in Ogulinsko Zagorje. It consists of two connected lakes: Small Lake and Big Lake. Some endemic species live in the lake and the nearby Rupećica cave: the olm (“ the human fish”) and telestes polylepis (“the light fish”). An old legend says that a dragon lived in the lake, and on one occasion it jumped out of the lake and grabbed a young girl. Then, St. George appeared and freed the astonished girl from the dragon’s embrace. There is a stone, near the lake, on which is “preserved” the hoof print of St. George’s horse.