Kapuas The Kapuas River as it flows through Pontianak Country Indonesia Physical characteristics Main source Mount Raya at Müller Mountain Range 2,278 m (7,474 ft) River mouth South China Sea 0 m (0 ft) Length 1,143 km (710 mi) Discharge Average rate: 6,000 m3/s (211,888 cu ft/s) max 7,530 m3/s (265,919 cu ft/s) Basin features Basin size 98,749 km2 (38,127 sq mi)