Hidden deep in the Slovak High Tatras, Green Duck Lake is a raw, untamed glacial tarn that rewards only the most adventurous mountain explorers. Sitting at 1,575.9 m above sea level in the Kačacia Valley, its emerald waters framed by sheer cliffs make it one of the most atmospheric spots in the entire range.

The lake covers about 2.58 hectares with dimensions of roughly 200 × 170 m, though the water level shifts noticeably with the seasons. Steep scree slopes tumble down from the northern cliffs of Gánok and Rumanov Peak directly into its shores, giving the surroundings a dramatic, almost primeval feel. Below the lake, the outflowing Kačací stream plunges over a rocky ledge to form the impressive 15-metre Kačacia Siklava waterfall. Nearby, two much smaller tarns — Malý Kačací Stav and Jelení Stavek — add to the sense of a truly secluded mountain world.

• There are no official marked hiking trails leading to Green Duck Lake — access is possible only off-trail, which in Slovak TANAP regulations is permitted solely for experienced mountaineers familiar with the rules.

• The lake lies within the Slovak TANAP protected area — off-trail travel requires experience and knowledge of current regulations.
• This site is not accessible to casual visitors; plan a trip only if you have solid high-mountain experience.

Local legend says that on Midsummer Night a golden duck appears on the lake and lays a golden egg — it is this charming folk tale that gave the lake its name.