The Dunwich Dynamo is an annual semi-organised, through-the-night bicycle ride from London Fields park in Hackney, London, England to Dunwich on the Suffolk coast. The distance is approximately 112 miles (180 km).

London Fields is a park in Hackney, London, although the name also refers to the immediate area in Hackney surrounding it and London Fields station. It is common land adjoining the Hackney Central area of the London Borough of Hackney. The park covers an area of 12.65 hectares, and includes sporting and recreation facilities. The park's history is recorded as early as the 13th century, and it has been known as London Fields since the mid-16th century.