The Niger River primarily flows in a northeastern direction before turning southeast, eventually making its way through several countries in West Africa and emptying into the Gulf of Guinea in Nigeria.
I know this based on geographical studies and maps of the river, which depict its course through countries such as Guinea, Mali, Niger, Benin, and Nigeria, showing its overall flowing path. Additionally, various hydrological resources and scholarly articles outline the river's direction and significant tributaries, confirming its flow from the Guinea Highlands toward the coast.