Laconia is a city in Belknap County, New Hampshire, United States. The population was 15,951 at the 2010 census. It is the county seat of Belknap County. Laconia, situated between Lake Winnipesaukee and Winnisquam Lake, includes the villages of Lakeport and Weirs Beach. Each June for nine days beginning on the Saturday of the weekend before Father's Day and ending on Father's Day, the city hosts Laconia Motorcycle Week, also more simply known as 'bike week', one of the country's largest rallies, and each winter, the Laconia World Championship Sled Dog Derby.