Finima Nature Park is Bonny Island's best travel reason: around 1,000 hectares of freshwater swamp forest, mangrove, sand, ponds, and coastal habitat set aside for conservation, research, and recreation. Wikivoyage notes monkeys, crocodiles, birds, and other wildlife; the park's own conservation brief stresses its role as one of the island's key remaining natural areas.
It is the kind of place where a guide matters. Ask ahead about walking trails, birding, and current access, and do not assume the park works like a city zoo. The setting, between delta forest and the Atlantic, is the draw.