(lĬgwesän´, lĬgwä´sän) , extensive swamp region, c.25 mi (40 km) long and 20 mi (30 km) wide, along the Pulangi River, S central Mindanao, the Philippines. There are fertile rice-growing areas and mangrove forests in the marsh. A game refuge and bird sanctuary (c.170 sq mi/440 sq km) was established there in 1941.
