Teddington Lock, on the western outskirts of London, is the end of the tidal reach of the Thames.
An obelisk 265 yards below the Lock marks the boundary of the jurisdiction of the Port of London Authority and the Environment Agency.
Before Teddington Lock was constructed in 1811 the river was tidal as far as Kingston. The pound lock was an early attempt to control the high tides, which in the 19th century were around ten feet above the level in Roman times. Today the tide flows up to Teddington but the half tide lock at Richmond prevents too strong a current and keeps the river level.
In 1888 – 89 a footbridge, built to the designs of G. Pooley replaced the ferry at Teddington. Two footbridges of different designs meet on the island at Teddington. The bridge spanning the river from the Middlesex bank to the island is a suspension bridge, while the shorter structure crossing from the Surrey bank has a girder design.