What is Oka (river)?
{{Infobox river | name = Oka | name_native = Ока́ | name_native_lang = | name_other = | name_etymology = <!---------------------- IMAGE & MAP --> | image = NN Spit from Fedorovskogo Embankment 08-2016 img2.jpg | image_size = 270 | image_caption = The Oka riverbank in [[Nizhny Novgorod]] | map = Okarivermap.png | map_size = 270 | map_caption = Map of the Volga watershed with the Oka highlighted | pushpin_map = | pushpin_map_size = | pushpin_map_caption= <!---------------------- LOCATION --> | subdivision_type1 = Country | subdivision_name1 = [[Russia]] | subdivision_type2 = | subdivision_name2 = | subdivision_type3 = | subdivision_name3 = | subdivision_type4 = | subdivision_name4 = | subdivision_type5 = Cities | subdivision_name5 = [[Oryol]], [[Kaluga]], [[Serpukhov]], [[Kolomna]], [[Ryazan]], [[Murom]], [[Dzerzhinsk, Russia|Dzerzhinsk]], [[Nizhny Novgorod]] <!---------------------- PHYSICAL CHARACTERISTICS --> | length = {{convert|1500|km|mi|abbr=on}} | width_min = | width_avg = | width_max = | depth_min = | depth_avg = | depth_max = | discharge1_location= | discharge1_min = | discharge1_avg = {{convert|1260|m3/s|cuft/s|abbr=on}} | discharge1_max = <!---------------------- BASIN FEATURES --> | source1 = | source1_location = [[Oryol Oblast]] | source1_coordinates= {{coord|52|21|45|N|36|13|20|E|display=inline}} | source1_elevation = {{convert|226|m|abbr=on}} | mouth = [[Volga]] | mouth_location = [[Nizhny Novgorod]] | mouth_coordinates = {{coord|56|19|55|N|43|58|53|E|display=inline,title}} | mouth_elevation = {{convert|67|m|abbr=on}} | progression = | river_system = | basin_size = {{convert|245000|km2|abbr=on}} | tributaries_left = | tributaries_right = | custom_label = | custom_data = | extra = }} The '''Oka''' ({{l