Zrmanja (pronounced [zř̩maɲa], Italian: Zermagna) is a river in southern Lika and northern Dalmatia, Croatia.

It is characteristic for its spring located on the bottom of very steep, almost 200 m high funnel shape rock called Misije.

Its main tributary is right bank Krupa river, rich in tufa and travertine rock sediments forming around its numerous waterfalls.

Rafting trips on Zrmanja take place in spring and autumn, while kayaks and canoes are used during low water level period of July and August.

[citation needed] The river was hit by an ecological disaster in December 2019 [2] when waste from a former alumina plant was washed into the karst underground.