ABSTRACT
Lake Nyasa, a Rift Valley lake and the third largest lake in Africa, is situated at the southern end of the Great Rift Valley. Lake Nyasa illustrates the problem of boundary delimitation in lakes as opposed to seas. In any water body defined as a sea, which is normally taken to imply a natural connection with the world's oceans, UN Convention on the Law of the Sea (UNCLOS) agreements apply. In lakes, of which 52 occur on international boundaries, there are no such guidelines. The original 19th-century boundary line was based on Anglo-German spheres of influence and an 1890 Anglo-German agreement described it as the eastern shore of Lake Nyasa. However, in practice German sovereignty extended to the median line until 1922 when Tanganyika came under British control. For the period 191634, official UK sources showed the boundary as a median line.
