The Thames Barrier is one of the largest movable flood barriers in the world. The Environment Agency runs and maintains the Thames Barrier as well as the capital’s other flood defences.
The barrier spans 520 metres across the River Thames near Woolwich, and it protects 125 square kilometres of central London from flooding caused by tidal surges.
It became operational in 1982 and has 10 steel gates that can be raised into position across the River Thames. When raised, the main gates stand as high as a five-storey building and as wide as the opening of Tower Bridge. Each main gate weighs 3,300 tonnes.
Explore our interactive timeline to see key dates about flooding on the Thames and the development of the barrier.
The information centre is a great way to learn more about the barrier. We also have conference facilities and packages for schools. See opening times, prices and directions.
View a video about how the barrier works, an interactive image of some of its features, a video about what would happen without flood defences, and information about the other flood defences protecting London.