A watercolour with graphite painting depicting the anchorage off the town of Bonny River.

The Bonny River, located in present-day Nigeria, was a major collection point for West African slavers. After 1808, in an attempt to shift the economy of the region away from slavery, a trade in palm oil was encouraged. A number of former British slave dealers quickly switched their business from human to palm oil cargoes. The King of Bonny, however, continued to supply some 30,000 slaves a year to Portuguese dealers during the 1820s and 1830s, which is roughly the period of this drawing.