Lake Charlevoix (top-most body of water) Lake Charlevoix is a lake in Charlevoix County in the U.S. state of Michigan. It is the third largest lake in the state with a surface area of over 17,200 acres (70 km²) and 56 miles (90 km) of shoreline. The maximum depth in the main basin is 122 feet (37 m) and in the south arm, 58 feet (18 m).