Lake Baikal is unique among the Great Lakes of the world in that there is fish life from its surface to a depth of over 1600 metres, its greatest depth, nearly all of which are endemic. Lake Baikal's great habitable depth range, combined with its great age, make it a unique natural laboratory for the study of adaptation to deepwater conditions. The present ichthyofauna of Lake Baikal includes 61 species and subspecies of fishes belonging to 32 genera and 15 families.