The Vilyuy (Russian: Вилю́й, IPA: [vʲɪˈlʲʉj]; Yakut: Бүлүү, Bülüü, [bylyː]) is a river in Russia, the longest tributary of the Lena. About 2,650 kilometres (1,650 mi) long, it flows mostly within the Sakha Republic. Its basin covers about 454,000 square kilometres (175,000 mi2).
