The Ay (Bashkir: Әй, Äy; Russian: Ай) is a river in Bashkortostan and Chelyabinsk Oblast in Russia, a left tributary of the Ufa. The river is 549 kilometres (341 mi) long, and its drainage basin covers 15,000 square kilometres (5,800 sq mi).^[1] The Ay freezes up in late October or early November and remains icebound until mid-April. The cities of Zlatoust and Kusa are along the river Ay. Along the banks of the river, there are many steep cliff sides and caves.^[2] The current of the river has been used for hydroelectric power. It is also possible to fish for pike, bleak, and carp, to name a few species.^[3]