The Cleethorpes trolleybus system once served the holiday resort of Cleethorpes, in Lincolnshire, England. Opened on 18 July 1937, it replaced part of the Great Grimsby Street Tramways, a tramway that had served both Cleethorpes and the neighbouring seaport of Grimsby. It was closed on 4 June 1960. By the standards of the various now-defunct trolleybus systems in the United Kingdom, the Cleethorpes system was a very small one, with only one route, and a maximum fleet of just 13 trolleybuses. It was operated jointly with the Grimsby trolleybus system.