Zeleni vir, Nature reserve in Primorje-Gorski Kotar County, Croatia.

Zeleni vir is a nature reserve in Primorje-Gorski Kotar with forested slopes and multiple springs that flow year-round. The terrain spans different elevations and supports diverse plant and animal life adapted to the constant moisture from water sources throughout the area.

Zeleni vir was declared a nature reserve in 1962 and lies at 302 metres above sea level near Skrad. In 1921 the building contractor Josip Lončarić built a small hydroelectric power station of the same name on the Zeleni vir stream; it then supplied electricity to the whole of Gorski kotar.

The name Zeleni vir means "green spring" in Croatian, referring to the spring and stream that feed the site. The narrow gorge within the reserve is called Vražji prolaz, "Devil's Passage", and the cave is Muževa hižica, "the man's little house". The small hydroelectric plant built on the stream in 1921 also carries the name Zeleni vir.

The reserve lies near Skrad in Primorje-Gorski Kotar County, at an elevation of 302 metres, and is reached on foot along several marked hiking and mountain trails. The narrow Vražji prolaz canyon, 800 metres long, and the Muževa hižica cave are both inside the reserve, so allow time to walk the trails rather than only the entrance area.

The stream at Zeleni vir powered a small hydroelectric plant built in 1921 by construction entrepreneur Josip Lončarić; it supplied electricity to the whole of Gorski kotar at the time. The plant shares the site's name and stands as an early example of waterpower use in this part of Croatia.