A regatta is a boat race or series of boat races. This can include both powered and unpowered ships. The term is also used to describe the festivities that occur during the lead up to the races, often a large social event for the town the regatta takes place in. One of the largest and most popular is the Henley Royal Regatta held on the River Thames, England. In the US, a famous example is the annual Head of the Charles Regatta, on the Charles River between Boston and Cambridge, Massachusetts.