Olguydakh

The Olguydakh (Олгуйдах; Олгуйдаах), is a river in Yakutia (Sakha Republic), Russia. It is a left hand tributary of the Akhtaranda, part of the Vilyuy basin. The river is 191 km long and has a drainage basin of 5450 km2.

The river flows across an uninhabited sector of Mirninsky District. An area where mysterious events reportedly took place lies near the abandoned Olguydakh village on the banks of the lower course of the river.

Course
The Olguydakh belongs to the upper stretch of the Vilyuy basin. It originates in the northeastern end of lake Toymoku (Тоймоку) of the Vilyuy Plateau. The river heads first northwards for a short stretch, then it bends and heads roughly southeastwards and southwards, meandering slightly for the remainder of its course. There are many small lakes in its basin. In its last stretch the Olguydakh turns to the southwest. Its mouth is at the confluence with the 227 km long Alymdya from the right to form the Akhtaranda, 75 km from its mouth in the Vilyuy Reservoir. There is a bridge of the Aykhal—Chernyshevsky highway over the Olguydakh.

Tributaries
The main tributary of the Olguydakh is the 80 km long Aallaakh (Ааллаах) from the left. The river freezes in mid October and stays under ice until mid May.