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
Grand Codroy Estuary estuary since 1974. The estuary consists of adjoining marine and intertidal habitats with an elevation no more than one metre. Four islands are located within the estuary, and the intertidal sandbars give way to mudflats "supporting rich growths of Zostera". The site is surrounded by cultivated grasslands. The marine area is shallow, at most two metres deep in intertidal areas, and somewhat deeper in the river channel. It is bounded by privately owned land, the Codroy Valley Provincial Park, and the Gulf of Saint Lawrence. Nearby are the Grand Codroy and Little Codroy rivers, which are popular fishing destinations. The