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
Exe Estuary on the west shore is the village of Dawlish Warren with its sand spit extending across the mouth of the estuary. Above this there are fewer settlements on the west shore, with just the villages of Starcross and Cockwood, both adjoining the lower portion of the estuary. The River Clyst also feeds into the estuary, just below Topsham. The River Kenn feeds into the estuary near Kenton. The soil is alluvial, derived from Devonian, Carboniferous and Permian rocks. The estuary is a Special Protection Area and SSSI. It is also a Ramsar site. The Exe Estuary is a site of