Born Aug. 23 (Sept. 9), 1825, in Arensburg, present-day Kingissepp, Estonian SSR; died Nov. 13 (25), 1886, in St. Petersburg. Russian naturalist and explorer of Siberia and the Far East.
In 1853-55, Maak took part in the expedition which first described the orography, geology, and population of the basin of the Viliui, Olekma, and Chona rivers. He studied the valleys of the Amur (1855-56) and Ussuri (1859) rivers.