Uvildy, Protected natural lake in Chelyabinsk Oblast, Russia.

Uvildy is a lake in Chelyabinsk Oblast, Russia, covering 68 square kilometers (26 square miles) and divided into three sections by a chain of islands. Around 50 islands form natural dividers across the water, creating smaller bays and passages between the lake sections.

Uvildy was designated a natural monument on 21 January 1969. In 1975, a drought in Chelyabinsk Oblast led to a canal being dug to divert its water into the Argazin reservoir; the lake level fell by 4 metres and did not recover until 2006, 31 years later.

The name derives from the Bashkir words uelde (hollow) and kul (lake), meaning "lake in a hollow"; tourist brochures also call it "blue bowl". In the 18th century, Pyotr Rychkov recorded the lake as Uyaley, noting over 500 islands and abundant fish. Today, 78 health resorts, holiday camps and private cottages line the shores.

Several access paths lead to the shore, and swimming, boating, and fishing are possible during warm months. The islands are mostly within sight, but caution is needed when going out on the water as weather conditions can shift quickly.

The lake's water is high in radon, at 473 nanocuries per litre, and radon springs feed it; a sanatorium on the shore uses these waters. In 1975 a canal was dug to send Uvildy's water to the Argazin reservoir during a drought, dropping the level by 4 metres; it took until 2006 to recover.