image creditMiners' lamps flash against the cold, damp subterranean walls and the tunnel ahead looks interminable. And if claustrophobia and darkness were not enough to deter the faint of heart, there are rats and the rising tide to think about while splashing through a foot of dirty water.
The Thames is not the only great river to have graced London in the city's long history. The Fleet was a clear sparkling river that for centuries ran from its source at Hampstead Heath to the Thames. Now its banks are found in a series of labyrinthine sewer tunnels, deep underground, for the brave and hardy to explore.The Presurfer
