Ulakhan-Botuobuya
The Ulakhan-Botuobuya is a river in Yakutia, Russia. It is a right hand tributary of the Vilyuy, with a length of and a drainage basin area of.
The river flows across mostly uninhabited territory of Mirninsky District. Botuobuyinsky Nasleg is located in its middle course. There is a pontoon bridge of the A331 highway stretch between Mirny and Udachny crossing the river just before its confluence with the Vilyuy.
Course
The Ulakhan-Botuobuya begins in the Lena Plateau at an elevation of. It flows first roughly eastwards and then northeastwards across the Vilyuy Plateau within a wide valley. Finally it bends again and heads northwards. The smaller Ochchuguy-Botuobuya runs roughly parallel to it further to the east. Finally the Ulakhan-Botuobuya joins the right bank of the Vilyuy from its mouth, a few miles downstream of the Vilyuy Dam. The river freezes between October and late May.The largest tributary of the Ulakhan-Botuobuya is the long Tas-Yuryakh that joins it from the right.