Puzzle Lake is a lake near Geneva in Seminole County, Florida. It forms the border of Volusia and Seminole counties. It is one of the lakes that make up the St. Johns River system. 1,627 yards (1,488 m) north of the lake is the mouth of the tributary, the Econlockhatchee River. It has a surface area of 1,300 acres (530 ha). 3.2 miles (5.1 km) downriver is Lake Harney, the start of the river becoming a wetland (upriver). It will become a narrow river again past Lake Poinsett in Brevard County. The lake is named after this because the navigable portions of the lake change seasonally depending on the amount of rainfall.