London: The Great River Race
Each year, one Saturday in September, crowds of people line the Thames through London, to watch one of the city's most unusual events; the "Great River Race".
Many big cities have one annual "marathon" race; London has two - one on dry land the other on water.
Technically, the Great River Race is not a marathon; it is slightly too short, and it is a boat race. Starting at Richmond, in the western suburbs of London, participants have to row their boats 22 miles, as far as the London docks, in the east.
The race is a relatively new event in the London calendar. The first race took place in 1988.
The idea was born in 1987, when members of the historic "Company of Watermen and Lightermen" (a very old professional organisation) rowed a replica 16th century royal barge from Hampton Court to the Tower of London
In 1988, they challenged other "traditional boats" to a race. Boats that want to take part must all be of traditional design, with at least four oars or paddles: furthermore, each boat has to carry at least one passenger.
In order to provide a thrilling finish to the race, a "handicap" system operates. At the start of the race, the slowest boats set off first, the fastest ones last.
In many ways, the Great River Race is a true race, in the traditional sense of the term - a race for amateurs, and a race without corporate sponsors.
1. What is the distance of the race?