Lewis Smith Lake is a reservoir in north Alabama. Located on the Sipsey Fork of the Black Warrior River, it covers over 21,000 acres (85 km2)  in Cullman, Walker, and Winston Counties. The maximum depth at the dam is 264 feet. The three-fingered reservoir has over 500 miles (800 km) of shoreline, and at full pool has a level of 510 feet (160 m).
The lake was created by Alabama Power with the construction of the Lewis Smith Dam. One of the largest earthen dams in the eastern United States, it stretches 2,200 feet (670 m) in length and reaches a maximum height of 300 feet (91 m). Construction began on November 25, 1957, and the dam entered service on September 5, 1961. The name honors Lewis Martin Smith, president of Alabama Power from 1952 to 1957.
Nearby towns include Bremen, Crane Hill and Dodge City in Cullman County; Curry and Jasper in Walker County; and Addison, Arley, Houston, and Double Springs in Winston County. Cullman and Winston County are dry (no alcohol is available) while Walker County allows alcohol sales with the limitation that no alcohol may be purchased on a Sunday. In 2017, Alabama passed a law that allows marinas with restaurants to serve alcohol regardless of what the law is in the county.
Tourist attractions are: Indian head cliff jump (30 ft), Castle Rock (40–50 ft), and the Castle.