Many worshippers are attending Nigeria's yearly festival dedicated to the Yoruba fertility goddess, Osun. Friday is the most important date of the two-week event.

They travel to the Osun Sacred Grove on the outskirts of Osogbo city, where the river is dotted with sanctuaries and shrines to mark what believers say is the settlement point for the ancestors of the Osogbo people over 400 years ago.

People say that the river saved Osogbo during a pre-colonial war between locals and the Fulani warriors. So the river is worshipped as a way of showing gratitude.

It's also the Unesco-protected home of 400 plant species, at least half of which have medicinal uses.