Ilasin Cave, Limestone cave in the Ishimbaysky District, Bashkortostan, Russia

Ilasin Cave, also called Ylasyn (Bashkir for 'falcon'), is a karst gallery in Middle Carboniferous limestone on the right slope of the Utynlygol dry valley, 1.5 km southeast of Khazinovo, Ishimbay district. Its main entrance is a 12 m wide, 7.6 m high arch in a 30 m collapse funnel, 170 m above the valley floor. The cave runs 487 m, averages 10 m wide and 5 m high, with an amplitude of 28 m, an area of 1025 m² and a volume of 5287 m³.

Ilasin Cave is a karst cave formed in Middle Carboniferous limestones on the right slope of the Utynlygol dry valley, 1.5 km southeast of Khazinovo in Bashkortostan's Ishimbaysky District. It was declared a nature monument in 1985, with a protected area of 100 hectares. The cave was surveyed and described in 1970 by V. I. Martin and L. N. Usoltsev.

The name comes from the Bashkir word ylasyn, meaning falcon, and the cave is also called Yelasyn officially and Sokolinaya in Russian. Eagles nest near one of the entrances, which matches the bird name. The cave is a nature monument of Bashkortostan.

The main entrance is an arch 12 m wide and 7.6 m high in a 30 m collapse funnel, 170 m above the floor of the Utynlygol dry valley, 1.5 km southeast of Khazinovo. A roughly 30 m ice-covered slope leads down to an 80 m gallery; four smaller entrances above lead into side passages. Summer temperature inside is 2–6 °C, so bring warm clothing.

The name Ylasyn means "falcon" in Bashkir, and eagles nest at one of the entrances. Above the main arch, four smaller entrances lead into side caves. The ceiling near the entrance is flat and covered with fringe-like hoarfrost, with organ pipes and small stalactites.