Japan? Australia? The U.K.?
Central African Republic — a small naval force is maintained on the Ubangi River, a tributary of the Congo River. The Ubangi River forms the country's border with Congo-Kinshasa, and is a significant transport route.
Rwanda — a small Navy patrols Lake Kivu, between Rwanda and the Democratic Republic of Congo. It was involved in the Second Congo War.
Serbia — following the recent split with Montenegro, Serbia became a landlocked country. Montenegro, whose territory sits by the Adriatic sea, has inherited nearly all naval components of the former union. Serbia however was not left without any naval property at all. It inherited a flotilla of river patrol and assault ships which operate on the Danube River. Currently it functions as a real seafaring navy would, with all the ranks and positions of a much larger and complex navy.
Uganda — the Ugandan navy operates on Lake Victoria.
Three of those are in Africa. There are more but I just listed some.