The Muna (Russian: Муна) is a river in Yakutia (Sakha Republic), Russia.

It is a left tributary of the lower reaches of the Lena and has a length of 715 km (444 mi).

[1] The river begins a little to the north of the Polar Circle at the confluence of the small rivers Orto-Muna and Ulakhan-Muna in the northeastern slopes of the Central Siberian Plateau at an elevation of 332 metres (1,089 ft).

It flows roughly eastwards in a deep valley and, after leaving the mountainous region it meanders across the Central Yakutian Lowland among almost 2,500 lakes, nearly parallel to the Motorchuna to the north.

From the end of May to June it flows at a high level, flooding sometimes in the summer.