The mountain water rat (Baiyankamys habbema) is a semiaquatic species of rodent in the family Muridae. It is found in West Papua, Indonesia and Papua New Guinea. Its natural habitat is rivers.

• Musser, G. G.; Carleton, M. D. (2005). "Superfamily Muroidea". In Wilson, D. E.; Reeder, D. M. (eds.). Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Johns Hopkins University Press. p. 1332. ISBN 978-0-8018-8221-0. OCLC 62265494.