According to the United States Census Bureau, the city has a total area of , of which are land and are water, comprising 24.54% of the city. Laconia is drained by the Winnipesaukee River. It is bounded in the southwest by Lake Winnisquam, and by Lake Winnipesaukee in the northeast. Laconia lies fully within the Merrimack River watershed. The highest point in Laconia is a hill in the northern part of the city, west of Paugus Bay's Pickerel Cove and just east of Route 106.