River Thames to the strong current of the river, but also other river users. Organised swimming events take place at various points generally upstream of Hampton Court, including Windsor, Marlow and Henley. In 2011 comedian David Walliams swam the from Lechlade to Westminster Bridge and raised over £1 million for charity. In non-tidal stretches swimming was, and still is, a leisure and fitness activity among experienced swimmers where safe, deeper outer channels are used in times of low stream. A Thames meander is a long-distance journey over all or part of the Thames by running, swimming or using any of the above
Tunnels underneath the River Thames Tunnels underneath the River Thames The table below lists many of the tunnels under the River Thames in and near London, which, thanks largely to its underlying bed of clay, is one of the most tunnelled cities in the world. The tunnels are used for road vehicles, pedestrians, Tube and railway lines and utilities. Several tunnels are over a century old: the original Thames Tunnel was the world's first underwater tunnel. The figure and list above leave out at least three tunnels: under the Thames Barrier; the 2.8m diameter tunnel carrying electricity cables from West Ham to the Greenwich Peninsula