The Borulakh (Russian: Борулах; Yakut: Боруулаах, Boruulaax) is a river in the Republic of Sakha in Russia.

It is a left hand tributary of the Adycha, of the Yana basin.

It usually freezes in October and stays under thick ice until June.

It heads first roughly north strongly meandering in its middle and lower course then is bends to the northeast around the Tirekhtyakh Range mountain area.

Finally it joins the Adycha downstream from the Nelgese, the largest tributary.