Lake Leelanau connects on the northwest to the Leland River, which runs for one mile to Lake Michigan. Between North Lake Leelanau and South Lake Leelanau the water narrows for about a mile near the unincorporated community of Lake Leelanau.
Lake Leelanau runs 21 miles (34 km) through the middle of the Leelanau Peninsula; it is about 1.5 miles (2.4 km) at its widest. The south lake includes 5,693 acres, the north lake includes 2,914 acres and the lakes have a total shoreline of about 41.2 miles. The south lake has an average depth of 24 feet and a maximum depth of 62 feet; the north lake has an average depth of 40 feet and a maximum depth of 121 feet.