River Thames shipping coming in and out of London, in 1732 it received the world's first lightship. This became a major landmark, and was used as an assembly point for shipping. Today it is marked by Sea Reach No. 1 Buoy. The River Thames contains over 80 islands ranging from the large estuarial marshlands of the Isle of Sheppey and Canvey Island to small tree-covered islets like Rose Isle in Oxfordshire and Headpile Eyot in Berkshire. They are found all the way from the Isle of Sheppey in Kent to Fiddler's Island in Oxfordshire. Some of the largest inland islands, for example
Wouri estuary are divided by the Dibamba River and by Monaka Bay and Island. About of the mangrove forest is within the Mouanko Reserve, which extends from the south shore of the estuary to the Sanaga River mouth. The mangrove "Rhizophora racemosa", which makes up over 90% of mangroves in Cameroon, reaches a height of in the Wouri estuary. "Nypa fruticans", an exotic species imported to Nigeria from South-East Asia, has been spreading quickly, encouraged by the local people. The mangrove forests are an important source of wood for making furniture and fences, for smoking fish and for fuel. The leaves of