Kuk, Mountain summit in Zakarpattia Oblast, Ukraine.

Kuk is a 1,361-metre mountain in the southeastern part of the Polonyna Borzhava massif in Ukraine's Carpathians. Beech forest with scattered spruce and fir covers its slopes up to 1,200–1,250 metres, giving way above to polonyna meadows with blueberry stands. Its main ridge runs south to north toward the neighbouring Polonyna Kuk (1,190 m), and its northeastern slopes are very steep and hard to cross.

In 1912 the company Dolhai Faipari Rt. built a forest narrow-gauge railway along the left bank of the Borzhava, linking to the Borzhava railway network toward Sukha-Bronka; a branch ran up the Bronka valley to the old-growth forests below Polonyna Kuk, 21 km in all. The Sukha-Bronka-Kuk section was dismantled in 1990. In 1930-1931 a 4.2 km line Kushnytsia-Lysychovo-Repynne was added, removed in 1986.

Writer Vasyl Hrendzha-Donskyi, a native of Mizhhiria and associate of Avhustyn Voloshyn, set his novella "Ilko Lypei" here. He fished for golden trout in the Koza stream on the mountain and once met the outlaw Ilko Lypei, an old schoolmate, whose story inspired the book. His line that skipping Kuk is like visiting Rome without seeing the Pope is often quoted locally.

A blue-marked trail crosses the summit between the village of Nyzhniy Bystry and the Polonyna Borzhava ridge; it continues the red Zakarpatskyi route from Volovets, which turns west at Polonyna Kuk (1,189 m) and descends to Mizhhiria. The north-eastern slopes are very steep and hard to pass, so plan the approach from the gentler side.

Writer Vasyl Hrendzha-Donskyi, a deputy of Avhustyn Voloshyn in Carpathian Ukraine, fished for golden trout in the Kozai stream on Kuk's slopes and met the outlaw Ilko Lypei there, a former schoolmate; the encounter became his novella "Ilko Lypei". In it he wrote that to be in the Carpathians without visiting Kuk is like being in Rome without seeing the Pope.